Blender Git Loki

Fix 'change path' opening file browser with wrong filter for sound strips

Changing path of a sound strip (select strip->C->'Path/Files') opened a file browser without filter for sound files, so sound files weren't visible.
Also, for movie/image files, now only movie **or** image files are visible in the file browser by default (instead of both).

Reported by @venomgfx, thanks!