Update commercial skip functionality

Updated code to support live commercial skipping and toggling of automatic commercial skipping. This request consists of a couple areas of change.

1. Added two new actions ACTION_TOGGLE_AUTO_COMMERCIAL_SKIP and ACTION_STEP_BACK_PREVIOUS_JUMP that can be assigned buttons. The first allows you to toggle auto commercial skip while watching a program, and the second allows you to jump back to the previous jump point in the case of an erroneous jump.

2. Update g_player to support the new actions and support .edl and .xml commercial files. Because of the way .txt commercial files are put out .edl and .xml are better choices for live skipping. I will update the wiki pages if approved to show how to output these files via comskip.

3. Add in filewatcher to watch the commercial file and reload when there is a change. This allows for skipping while a file is currently being recorded. Say for example I start watching a show 15 minutes after the start, I now should get auto skipping throughout.

4. Update commercial skipping logic such that if you for some reason end up in a commercial segment with auto skipping enabled you will be skipped right to the end of the segment. Previously you had to be watching up to the skip point for the skip to work. Now if I skip into the commercial segment the algorithm will quickly skip me to the end.