aux.py: add is_file_local().
Rename global_setting to globals.
subtitle.py: initialize fetched_subtitles.
mplayer.py: global_settings -> globals.
mplayer: add is_file_local().
mplayer/mplayer.py: initial codes for mutiple backends support.
mplayer/media.py: import aux.which.
mplayer.pyz: rebuild against recent changes.