Repobee

This is a minor release with some new functionality and a bunch of bugfixes.

Features
* bce95df Add a `--quiet` option to silence stdout, warnings and errors (650)
- The `-q|--quiet` option is added to every command and stacks up to three times. See the PR 650 for details.
* 7ae456a Hide token by default in `config show` command (642)
- Previously, the secure token would show up when running `config show`, which is an annoyance for demos. Now, it's replaced with `xxxxxxxxxx` by default, and one must add the `--secrets` option to show it.

Bugfixes
* d0d9e25 Allow cloning of empty student repositories (654)
- Previously, there would be an error message on cloning empty student repos, and the repositories would not show up in the working directory. Now they do.
* db825f5 Fix the broken pylint plugin (651)
- This is a reimplementation of the pylint plugin, which did not work at all with RepoBee 3. PRs to enhance it are welcome!
* dcedab4 Fix crash in javac plugin when ignore list is None (643)
- The crash would occur if the `--javac-ignore` option was not specified.
* fe7030c Make install script look for more Python executables (637)
- The install script now looks for the following variations of the Python executable: `python3.9`, `python3.8`, `python3.7`, `python3.6, `python3`, `python`. They are all checked to actually be Python 3.6+ before being chosen as an interpreter.

Other
* df53a2e Group related CLI arguments (639)
- This is a much needed cleanup of the CLI help menus, making for a better user experience. The help sections are actually readable now. See 639 for an example.

There was a breaking bug in RepoBee 3.0.0, and so it has been removed and replaced with this release. For all intents and purposes, this release represents RepoBee 3.0.0.

Upgrading from RepoBee 2.x
For users upgrading from 2.x, do the following.

* Make note of your current settings
- You will need these when configuring RepoBee 3
- `repobee show-config`
* Uninstall any RepoBee-related packages with `pip`
- Find packages with `python3 -m pip list | grep repobee` and uninstall them
- Make sure to at least uninstall `repobee` and `repobee-plug`
- `python3 -m pip uninstall -y repobee repobee-plug`

When that's done, you're ready to start with RepoBee 3. Go to [repobee.org](https://repobee.org) and follow the instructions.

Changelog
Features
* RepoBee can now be installed with an install script, see https://repobee.org
* Installed RepoBee comes with a plugin manager
- `repobee plugin -h` for info
* RepoBee can now be used programmatically
- E.g. `import repobee; repobee.run(["config", "show"])`
* c72188b Add support for default branch names other than master (631)
* eb97872 Add --version-spec option to `manage upgrade` (607)
* 072d1b8 Add tab completion for bash and zsh (597)
* 7ed23fa Allow config wizard to configure plugins (566)
* db5eb5d Add RepoBee distmanager plugin, fix 564
* 691878d Group command extension arguments by plugin, fix 563
- This leads to less cluttered help sections when using command extensions
* 5abe06d Revamp user feedback (550)
- User feedback is now much more refined, with progress bars everywhere!
* 3014d1f Automatically assign parsed args to plugin command instances (526)
* 9b9bed1 Add workdir argument to repobee.run (524)
* 66293b4 Allow plugin commands to add categories (516)
* 2f3dc41 Wrap plugin command settings in object (511)
* 0b1abd6 Add mutex groups to plugin commands (510)
* c342753 Add positional arguments to declarative plugin commands (509)
* 07c29c3 Add run function to repobee module (505)
* 3181364 Allow plugin commands to add options to core commands (504)
* c184fc0 Implement rudimentary installer (476)
* 9f0e5ce Set logfile logging level to DEBUG (475)
* 9bc7d07 Add support for single-file plugins (456)
* 1c6427e Expose functionality for testing plugins in repobee module (449)
* 8b7861c Add --config-file preparser option (440)

Breaking changes
* 4c285fa Drop Python 3.5 support (429)
* 0fdf418 Remove the --show-all-opts functionality (635)
* fa19a3b Add explicit option to allow use of local template repos (629)
* 76488e7 Remove safety prompt from `config wizard`, fix 600
* 8b064cc Remove plugins from config file (599)
* af8ecf0 Rename MASTER_ORG and REPO_NAMES base parsers (591)
* c9534e9 Rename "master org name" to "template org name" (586)
* a35f1eb Rename master repo names to assignments/assignment names (583)
* c6a1f8d Make the command function's api argument optional (581)
* 15db979 Refactor post_clone and pre_setup hooks (570)
* 52d503c Redesign the platform API (544)
* 2d8eeca Rename DEFAULTS header to repobee (535)
* 27f82e4 Remove create_extension_command hook and related containers (528)
* 9cb6d54 Replace task hooks with simpler hooks (523)
* 23237da Replace .cnf config file suffix with .ini (508)
* 5444637 Implement declarative extension commands (497)
* 4752a56 Revamp CLI (495)
* 0dda4d0 Simplify extension command callback return value (482)
* f0295e4 Remove REPOBEE_OAUTH environment variable (457)

Release notes
Beta release with some minor bugfixes.

Bugfixes
* Make `teams create` actually do something (614)
- `teams create` did not have any effect in beta 2, now it works as it should
* Fix crash in `plugin uninstall` command (612)

Some bugfixes and quality-of-life improvements.

This is the first beta release of RepoBee 3. This marks a feature freeze of the current functionality. Changes will now be limited to bugfixes and documentation improvements.

* `--discover-repos` option for `clone`, `list-issues` and `close-issues`. It can be used instead of `--master-repo-names` to dynamically discover all repos associated with the specified students/groups.
* `create-teams` is back, such that a RepoBee user can create student teams without creating any repos.
* The plugin system has been completely overhauled, see [repobee-plug v0.12.0 release notes](https://github.com/repobee/repobee-plug/releases/tag/v0.12.0) for details.

Features
* c18abf6 Add `--discover-repos` option to close-issues, fix 412
* cb466df Add `--discover-repos` for `clone` and `list-issues` commands (407)
* 0cd3352 Add create-teams command, fix 384
* bd81e6c Show hook results for extension commands, fix 411
* 26b0692 Add support for BaseParser.REPO_DISCOVERY, fix 410
* 7621b7b Warn on use of deprecated hooks, fix 398
* 93d2192 Use clone_task hook in clone command, fix 394
* 4322335 Use setup_task hook in update and setup commands, fix 392
* 9cd890a Prefix javac plugin CLI options with --javac, fix 388
* 75ba998 Show plugin version in help section, fix 378

Documentation
* f252a98 Update docstrings of platform API implementatins, fix 414
* 602e007 Update roadmap
* 76686b1 Fix incorrect type hint
* b0e32ba Add missing documentation to command subpackage, 403
* fbfcd9c Add brief README files to subpackages
* 8d4a1f7 Update the roadmap
* c403823 Add note about planned changes to plugin system
* d6656d4 Update roadmap in README
* e4bd0cb Add 3.8 to supported Python versions badge
* 4da175e Remove redundant information in README
* 6a1d41b Update overview section in README
* bdf137c Add RepoBee logo

Refactorings
* f6a7359 Update javac plugin to use config_hook again
* bd87574 Migrate built-in plugins to new task hooks, fix 399
* 354db21 Support the new Result tuple, fix 409
* 97cda6e Redesign command.issues.list_issues, fix 405
* 67fd5f0 Redesign commands.repos.clone_repos (406)
* 80a7998 Refactor command module into subpackage, fix 403
* cfc8bd5 Refactor cli module into subpackage, fix 402
* fa826ab Adapt to repobee_plugs lessened API surface
* 0ee4d7b Adapt to the revised deprecation system in repobee-plug
* 569a4ea Run tasks on copies of repos instead of on the actual repos, fix 393
* 2171b4e Adapt plugin usage to final Task definition, fix 397

Other
* 3970daa Pin repobee-plug version to 0.12.0
* a1faa7b Exit early on integration test failures
* 31b6981 Run macOS build without caching and only on Python 3.5.4 (387)
* 53e450d Add Python 3.8 to Travis build matrix (381)
* 15d02cf Measure coverage on integration tests (379)