Fix incomplete PHPDoc comments, add missing @covers and such

Authored by thiemowmde on Thu, Sep 14, 8:51 AM.

Description

Fix incomplete PHPDoc comments, add missing @covers and such

  • Fix all incomplete @param.
  • Use generic "Generator" type hints because this is all the callers need to know.
  • Add @covers to all tests.
  • Have at least the most basic @license header in all files.
  • I'm also adding a few newlines in places where I believe it improves readability, e.g. between @param and @return.

Change-Id: I99fee18cf72bb26a65350a73f207df8e94230c66