It's somewhat annoying to keep restarting rage in order to manipulate the playlist. Having a keybind for clearing it
goes a long way for usability.
Test Plan: Add files. Hit c. Add more files. Skip around in the playlist. Clear. Add.
Reviewers: etrunko, raster
Differential Revision: https://phab.enlightenment.org/D1484
* fix mem leak of vid content