Properly compute the CEGUI_INCLUDE_DIRS
Properly compute the CEGUI_INCLUDE_DIRS

We do this by including *only* the parent
directories of the "CEGUI/" subdirectory,
so that we won't get into compilation errors.

Also, set more explicitly the docstrings

cbeck88/cegui-mirror,RealityFactory/CEGUI,arkana-fts/cegui,arkana-fts/cegui,cbeck88/cegui-mirror,arkana-fts/cegui,cbeck88/cegui-mirror,cbeck88/cegui-mirror,RealityFactory/CEGUI,cbeck88/cegui-mirror,arkana-fts/cegui,RealityFactory/CEGUI,RealityFactory/CEGUI,arkana-fts/cegui,RealityFactory/CEGUI