Added "DebugText" setting that causes TextComponents to draw a background of their size + the area of their TextCache.
It can be toggled with Ctrl-T when running with --debug.
Added std::cout output when specifying overriding home path.
SDL_mixer is not in the standard SDL distribution. The mixing is now
done using regular SDL_Audio functions. AudioManager is converted to a
singleton and std::shared_ptrs are used for all Sound objects. Note that
for GCC "-std=c++11" might need to be added to the CMAKE_CXX_FLAGS.