(@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