* src/video_output/video_output.c, src/input/decoder.c, include/video_output.h: try to reduce i_sar_num/i_sar_den a bit hader to prevent overflows + remove p_vout->b_override_aspect which isn't used anymore.

set the samplerate before the format. The open of the device will fail when trying to set the sample rate to a value the soundcard doesn' support afet having set the format to fl32. Now, we will fall back to s16l if the device doesn't support the rate in fl32.

Closes #414 

* modules/video_output/directx, modules/video_output/x11: take cropping into account when reporting mouse coordinates.

service discovery and demux modules.

   isn't really efficient)

* src/video_output/*: re-implemented InitWindowSize() using fmt_in.i_sar_num/den and moved it to vout_intf.c where it can be called again after crop or aspect ratio changes.

* src/libvlc.h, src/video_output/vout_intf.c: added crop config option + changed --monitor-aspect-ratio into --monitor-par (pixel aspect ratio). It makes a lot more sense since lots of widescreens still have square pixels.

* modules/video_output/directx/directx.c, modules/video_output/directx/glwin32.c, modules/video_output/opengl.c: support on-the-fly aspect-ratio changes.

plugin.cpp: on activation, set width and height in VLC configuration variables with plugin actual geometry, this prevents video rescaling when starting video

mkv.cpp: get ready to support pixel cropping (top/bottom/left/right) when it will work from the demuxer in VLC