Cucumber expressions support

[gasparnagy]

WIP: Cucumber expressions support

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue).
• [x] New feature (non-breaking change which adds functionality).
• [x] Breaking change (fix or feature that would cause existing functionality to not work as expected).
• [ ] Performance improvement
• [x] Refactoring (so no functional change)
• [ ] Other (docs, build config, etc)

Checklist:

• [x] I've added tests for my code. (most of the time mandatory)
• [x] I have added an entry to the changelog. (mandatory)
• [x] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.

[gasparnagy]

@SabotageAndi The PR is finally getting closer to finish, so probably it is worth starting to review it. There are a few open points (you will see TODOs), that we should discuss and I will make some further exploratory testing.

We should consider calling this v4.0 BTW -- but let's discuss this.

[SabotageAndi]

@gasparnagy not sure I find time to have a look at this week. But next week should be possible.

[gasparnagy]

@SabotageAndi OK/thx. I am on a conf Thu-Fri.