Don't use IMadVRSubclassReplacement

This interface is not supposed to be used like that.
Thus, to provide mouse messages to madVR, go back to using
CMainFrame::WindowProc()
Hide the seekbar in capture mode since it can never be used.
MainFrm: fix rare black screen issue with madvr

Or more like hack around for now, it needs to be be discussed
with the author of madvr