New classes:

1.
TGLBoxPainter - implements "glbox" option for TH3, shows bin contents as
boxes, which sizes are proportional to bin content. "glbox1" is the same,
as previous, but with spheres instead of boxes. Slices (XOY/YOZ/XOZ)
are now drawn as sets of rectangles.

2.
TGLLegoPainter. Changes: removed all stuff, which works with gl
projections, modelview transformations, textures, etc.

3.
TGLPlotPainter. Added common parts of different painters:
generic Paint function, PlotSelected, etc.

4.
TGLOrthoCamera. Added operations, required by gl hist painters.

5.
TGLHistPainter. Class completely changed (previously known as
TGLPadHistPainter).

6.
TGLPlotBox. New class, draws back box for different kinds of plots,
highlights planes which are under cursor, makes some sizes calculations
(converts 3d into 2d coords) etc.

7.
TGLSurfacePainter. New class, for different surf options.
Supports cartesian, polar, cylindrical and spherical coords.
Slices (XOY, YOZ, XOZ), projections.

8.
TGLTF3. New class, draws TF3. No slices available now.

9.
TGLUtil. Added new auxilary classes
TGLLevelPalette, TGL2DArray, functions, required by different plot
painters,
TGLEnableGuard and TGLDisableGuard removed from RootGL namespace into
global namespace.


git-svn-id: http://root.cern.ch/svn/root/trunk@16183 27541ba8-7e3a-0410-8455-c3a389f83636