src/control/media_instance.c: Don't wait to have modulo something, to forward the time, that could be crazy.

* Implement MediaInstancePositionChanged and MediaInstanceTimeChanged accurately.
control/event.c:
* Register the all event types.
* Don't strdup() in libvlc_event_type_name().

media_instance.c: Fix the position callback to retun the time. (Next time, we'll fix it to return the position).

MacOSX/Framework/VLCTime.m: Fix a segfault because of a missing retain. Create a real null time. Code simplification.

* add a 'graphite' button set including the facilities to switch the theme at runtime (closes #1379)

MacOSX/Framework/VLCLibrary.m: Default the use of the opengllayer video output module. Don't be verbose by default.

Only the file access uses this, but I don't like "wild" callbacks into plugins.