Show targetname in entity info bubble.

Also render info bubbles of selected entities on top.
Render world bounds in 3D view.
Add simple layer system and list view.
Improve performance of face change notifications.

Notifier now takes a list of faces instead of the individual faces.
Added support for adding and removing layers.
Adapt test cases.
Fixed some unused variable warnings.
Implemented add / remove layer buttons.
Implemented moving objects between layers.
Improved layer handling.

- Select the correct layer for duplicated, clipped, and resized objects.
- Select the correct layer for brushes belonging to brush entities (no mixing of layers within brush entities).
Adapted test cases for adding and removing objects.
Added context menu to layer list in map inspector.
Made mini map and layer list resizable.
Handle layers when moving brushes between entities.
Added buttons to layer list.
Minor changes to layer list layout.
Improved layer list toggle button images.
Improve layout issues of layer list on Windows.
Merge branch 'layers_and_groups' of z:\Documents\Code\TrenchBroom into layers_and_groups

Conflicts:
	common/src/View/wxUtils.cpp
Use white background on toggle button images.