libvlc: rename all libvlc_MediaInstance in libvlc_MediaPlayer and libvlc_MediaDescriptor to libvlc_Media
Signed-off-by: Pierre d'Herbemont <pdherbemont@videolan.org>

Signed-off-by: Pierre d'Herbemont <pdherbemont@videolan.org>

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

control/event.c: Properly implement libvlc_event_type_name, instead of relying on a non-working macro.

control/event.c: Make detach-ing from an event safe: A detached callback can't be called after event_detached. Add an internal event_detach_lock_state, to bypass this feature.

control/event.c: Make sure the callback list is initially set to NULL. (Likely fix the crash reported by Olivier Aubert).

- libvlc APIs: bug fixing, and please note that exception argument is OPTIONAL (can be null), do not use exception to control API flow unless you created your own

libvlc: Rename input to media_instance. And add the possibility to create a medi_instance from a media_descriptor.

Libvlc event: Support for event extra information passing. And register to "time" event rather than "position".