* modules/gui/wxwindows/preferences.cpp: fixes some alignment issues in the config options panel.
* modules/gui/skins/src/*: use (AOUT_VOLUME_DEFAULT * 2) as max volume.
* modules/video_output/directx/*: use inheritance for the direct-always-on-top object var.
   Added Ctrl+left/right arrows as shortcuts for seeking in 1 min chunks.
* modules/mux/mp4.c: fixed the audio/video sync.