Message_Printer - define GetTraceLevel()/SetTraceLevel() methods in base interface.
Implement message gravity filter in Draw_Printer.
Add new Draw Harness command dtracelevel to show/change message gravity filter.
Redirect default messenger to Draw_Printer within TKDraw instead of TKXSDRAW
Draw::Commands() - assign Draw_Printer only once
License statement text corrected; compiler warnings caused by Bison 2.41 disabled for MSVC; a few other compiler warnings on 54-bit Windows eliminated by appropriate type cast
Wrong license statements corrected in several files.
Copyright and license statements added in XSD and GLSL files.
Copyright year updated in some files.
Obsolete documentation files removed from DrawResources.
