* move watermark options into watermark selector
* fix graphics engine overlay performance
* more refactoring
* add some tests for existing watermark selector behavior
* remove extra ffprobe call on all watermarks
* remove a bunch of unused code; add failing tests
* implement new watermark selection
* add tests for new selector
* probably sufficient (though verbose) test coverage
* more tests
* remove some unused code
* simplify watermark selection
* remove old selection code and tests
* more tests
