[Feature] Support cucumber expressions

[blaisep]

(@jenisys , this is placeholder issue, feel free to modify/delete)
Relates to cucumber-expressions upstream issue 27

Link to the "hackathon fork" so we can work without disturbing the upstream.

• Implement the functionality for cucumber-expressions
• Provide unit tests for cucumber-expressions
• Prepare feature/*.feature file(s) describing how cucumber expressions can be used in behave.
• update the regex doc to include a reference to the new expression format.
  NOTE: regex doc page should probably stay the same (because you are not changing regex(s); you are providing an new dialect => Use new page as summary in appendix if needed).
• Add a doc page for the new features.
• Information for the "New and Noteworthy" page that shows an example and points to the detailed description page

Edit: adding @bittner for visibility

[jenisys]

SEE ALSO:

• https://github.com/cucumber/cucumber-expressions
• PR: Cucumber Expressions for Python cucumber/cucumber-expressions#65

[aslakhellesoy]

Great work @mrkaiser!

Why did you choose to make a separate library rather than submitting a PR to Behave?

[mrkaiser]

I wanted this to be available now. I didn't want to wait on a behave release sometime in the future. If I'm going to update the language service to have pythonic ParameterType support, this need to be available broadly.

If pypi releases of Behave start becomming common place, I would prefer to merge this functionality into Behave to simplify usage and adoption.