Changeset 2131 for code/trunk/src/orxonox/objects/worldentities

Added CMakeLists.txt to every subfolder and adjusted accordingly.
The CMake script I have written can be used as follows:
ADD_SOURCE_DIRECTORY(_source_list directory) # Adds a new source subdirectory where _source_list is the name of the source list in CURRENT folder
ADD_SOURCE_FILES(_source_list) # Adds the source files in a subdirectory to the source list in the super directory (has to be called!)

Note: When adding more subdirectories in a subdirectory, call ADD_SOURCE_FILES after ADD_SOURCE_DIRECTORY!