Wfpm

* added `params.container` that allows runtime substitution of container image when needed
* adjusted how default container registry is set
* added `logger` to the `project` object, in preparation for more detailed logging
* eliminated dependency on `ctx` in all commands
* updated README

* more generalized template generation for workflow packages, resulting starter template workflow is always functional provided user specifies valid dependencies
* made `diff` process used in `checker.nf` smarter, works for both gzip'd and original expected files
* updated README to reflect new features, such as `workon` and the elimination of manual creation of git branch for newly created package

* implmented `wfpm nextver` command, it supports updating an existing package to a new version
* added tests for `nextver`
* added two new methods in `Git` object
* updated README

* first pass implementation of the `wfpm workon` command, which is the start point of ensuring package code updates to be done only on the correct git branch
* `wfpm install` and `wfpm test` make use of the new `workon` package feature, install dependencies or run tests for the currently worked on package
* pakcage release tag convention update: from `<package_name>.<version>` to `<package_name>.v<version>`, compatibility code in place to ensure package installation works with both
* Git object contains more useful info, including user name/email, branches, tags

* removed not much needed Config (may need later)
* added Git for git config and operations (WIP)

* clean separation between `Config` and `Project`
* `Project` object is much more useful now with lot of information populated at init time
* auto-config is able to pickup `user.name`, `user.email` from git config
* detect `git` installation and configuration readiness
* use `questionary` to collect user inputs from the prompt, which is colorful and allows finer control
* build dependency graph before installing dependent packages, able to handle nested dependency with automatic circular detection (thanks to `networkx` built-in support)
* as part of the creation of a new package, dependencies are installed / tested automatically (instead of done manually earlier)
* generate workflow main script without hardcoded `include` statements (still have room for improvements)