modules/gui/wxwidgets/dialogs/updatevlc.cpp : clean up

(i just had to find the suxor thread exemple in video_output.c :p )

                   to use in interfaces)
                   The downloadable plugins part still needs some work.

modules/control/rc.c : add function to query updates (mainly used for testing)

modules/gui/wxwidgets/* : update pannel.

This one is slightly dangerous as it can happen over and over again during
normal operation.

with proper configure checks

* If input file in current dir specified, then retrieve CWD when we try to look for subtitle files. fixes #463
* When probing the autodetected files, probe them in the Locale, not in UTF-8. refs #528

* Revert the Quartz disabling.

(ie. most) automake users are used to.
If you DO want NOT to use maintainer mode you are free to pass
--disable-maintainer-mode to configure.