* src/video_output/video_output.c, include/video_output.h: modified vout_Request...

* src/video_output/video_output.c, include/video_output.h: modified vout_Request() to take into account the
filter chain. If the filter chain has changed, a new vout will be respawned allowing to switch filters on
the fly. This is still a bit hacky but to do it nicely will require implementing inheritance in object
variables.
* modules/video_filter/deinterlace/deinterlace.c: added a "deinterlace-mode" object variable to allow
switching deinterlace modes on the fly.
* modules/gui/gtk/menu.c: updated the deinterlace menu.
* include/vlc_common.h: compilation fixes for gtk_main and gnome_main.