* modules/gui/macosx/output.m: updated part of the Stream output dialog
* modules/demux/util/sub.c: removed sub_detect() and moved the sub-file and
  sub-autodetect file options to src/input/input.c
* src/input/input.c: added the moved options and use them to add subtitle
  tracks.
* src/libvlc.h: description strings etc for sub-file and sub-autodetect-file
* src/input/subtitles.c: new subtitles_Detect() largely based on the
  code used by MPlayer. Adapted for coding style and structure differences.

The autodetect routine can now detect multiple subtitle files and assigns scores
based on their names. if they much well enough they are sorted based on their
score. It will then return this set, and they will all be added as SPU tracks
to the current stream. The (un)selecting of these tracks will need to be fixed
because they all get assigned the es id 0xFF currently.