Don't unload the library in RCCpp's destructors because Context will try to deallocate subsystem's and factory's memory and we need the library to be still loaded at that moment.
It turns out that as RCCpp is a subsystem, so either we change the destruction order in Context.cpp so that it deallocates first the factory and then the subsystem, or we simply remove the unloading of the library.
To avoid causing any other bugs changing the order, let's be conservative.
Add AngelScript's and Lua's include folders to the Makefile.