Fixed build errors and warnings

Plox pull in the INCLUDE_DIR bit as some of us in the world don't want to make symbolic links in /usr/local/include to our X11 stuffs at the very least.
Also fixed build error due to not including cstdlib in department.hpp due to use of stupid inline function definitions. If you don't want more include files to happen when you include files, you should have thought about that before you inlined the function definition.
Fixed my own issue with inline declaration warning on my version of clang (with libc++ :P )