From Timur Pocheptsov:

-TGLPixmap - removed and replaced by TGLViewer (most of the TGLViewer
    functionality is available in pad now);
-TGLHistPainter - zooming/panning added for legoes/surfaces;
-TGLViewerEditor - TGLViewer's editor for pad (lights/clipping/guides
    manipulation).

-TRootCanvas :
  minor changes to support mouse wheel event in gl viewer in a pad

-TCanvas :
  a)changes to process keyboard events correctly
  b)changes to process mouse will events

-TVirtualViewer3D :
  changes in interface for TGLManager (win32 implementation of TGLManager
  requires some functions and cannot be dependant from TGLViewer)

-Added class TVirtualGLManipulator - base for TGLManip - again, required
 mostly by TGWin32GL.


git-svn-id: http://root.cern.ch/svn/root/trunk@14203 27541ba8-7e3a-0410-8455-c3a389f83636