2.5

More toolbar functionality for workflow review.

- Split the region in two parts, bottom has the Tool Properties, the
  top part shows 2 panels, one for python defined tools, other for a
  "tool shelf" which (later) will get saved in files.
- Added a full context driven framework for this toolbar, showing 
  the tools depending on 3D window 'mode'. Both python defined tools
  as the shelf respect this. So - for example - you will see different
  tools in editmode mesh, as in vertex paint mode, etc.
- First template for the python tools will be committed after this commit;
  it has placeholder tools to just show/test functioning.

NOTE: if you had saved a layout that shows tools region, open/close it
once to get the new region created for properties.

TODO:

- Moving paint properties to tool settings
- Test a layout with horizontal toolbar (without properties)
- Bring back floating panels, and put tool-properties here. (as option)

source/blender/blenkernel/intern/screen.c

@@ -78,6 +78,8 @@ static void spacetype_free(SpaceType *st)
 	}
 	
 	BLI_freelistN(&st->regiontypes);
+	BLI_freelistN(&st->toolshelf);
+
 }
 
 void BKE_spacetypes_free(void)