Updated CMake files to facilitate compilation on Windows.

- Added code for linking to debug libraries for libRocket for Debug projects (otherwise there will be compile errors). Previously I had resorted to manually changing the libraries which were linked in the Debug projects. [FindRocket.cmake]
- Added code for finding mspack library paths (pkg-config doesn't work very well on Windows). [CMakeLists.txt]
- Removed FindCEGUI.cmake since it is no longer required.