Dunamai

* The `from` command will print a warning for shallow Git repositories.
This becomes an error with `--strict`.
* The `Version` class has a new `concerns` field to indicate warnings with the version.
Right now, the only possibility is `Concern.ShallowRepository`.

* Fixed outdated reference to `pkg_resources` in the docstring for `get_version`.
* `CHANGELOG.md` and `tests` are now included in sdists.

* Updated `Version.parse` to better handle PEP 440 versions produced by Dunamai itself.
Specifically, in `1.2.3.post4.dev5`, the post number becomes the distance and the dev number is ignored.
In `1.2.3.dev5`, the dev number becomes the distance.
* Added `increment` argument to `bump_version` and `Version.bump`.
([Contributed by legendof-selda](https://github.com/mtkennerly/dunamai/pull/54))
* Fixed Git detection when there is a "dubious ownership" error.
Previously, `from git` would report that it was not a Git project,
and `from any` would report that it could not detect a VCS.
Now, both commands report that there is dubious ownership.
* Improved error reporting for `from any` VCS detection.
The error now specifies which VCSes were checked and which were not found to be installed.

* Added compatibility with Git versions as old as 1.8.2.3.

* Fixed Git 2.7.0 compatibility by changing `git log --no-show-signature` to `git -c log.showsignature=false log`.

* Added a `strict` option to prevent falling back to `0.0.0` when there are no tags.
* Added support for `.git_archival.json` files created by `git archive`.
* Added support for `.hg_archival.txt` files created by `hg archive`.