* modules/misc/sap.c: added sanity checks and more coding style fixes

* src/video_output/video_output.c:
  Video filters can now be enabled on the fly (vout is respawned)
  You need to var_Set( p_vout, "filters", psz_yourvalue)
      for this

* modules/gui/wxwindows/interface.cpp : Enable the adjust filter on the fly