Enhanced support for reStructuredText format in library documentation #2507

reStructuredText has been supported as library documentation format since RF 2.7.5 (#489) and RF 3.0.1 (#2448) adds support syntax highlighting using code blocks. It is still not that convenient to use reST, especially if you'd like to use the same docs also with other tools consuming reST like Sphinx. Features that should still be added:

• Highlight literal blocks created by using :: automatically in Robot Framework syntax. This should be
  done so that there's no need to add test case table header or other boilerplate. Supporting this would
  be very convenient:

  Example::
  
      ${result} =    My Keyword    argument
      Another Keyword    ${result}
  

• Support reST's normal link syntax with a trailing _ when referring to other keywords or section titles. In other words, keywords and titles should create implicit link targets that can be used everywhere in the docs.

• Support using explicit link targets created in introduction everywhere in the docs. Related to the above.

• Format arguments documented using Sphinx supported syntax (at least one of them) nicely.

If the above are implemented, reST would become a very attractive format for documenting larger test libraries like Robot's own standard library and SeleniumLibrary (see robotframework/SeleniumLibrary#389). The problem implementing the above is that docutils APIs aren't particularly easy to use externally. Sphinx is able to support similar features in its domain so this shouldn't be impossible for us either.