- TGPictureButton is added to GuiBuilder widget pallete.
  TGPictureButtons now can be created via widget pallete or
  just by browsing xpm,gif,jpeg,png,tiff files with TBroswer
- Increase a size of TGuiBuilder
- minory fixes in TGuiBuilder
- bld_image.xpm (by Leonardo da Vinci ;-) added to ROOT icons


git-svn-id: http://root.cern.ch/svn/root/trunk@10340 27541ba8-7e3a-0410-8455-c3a389f83636