Added a file for client side utilities.

It contains currently an operator== for `SDL_Color`s.
The Label cache regeneration is now more sophisticated.

Should the client code be setting a member to what it was in the first
place, the cache is *not* regenerated.
Small change in the order of actions taken by Label's move operator=.

By moving the cache move to the end we counteract any of the members
initiative to destroy the cache, since it doesn't no better. In other
words, the changes to the members will most likely cause an invalidation
of the cache, because the good, alive and awesome one was moved in
already *it* is going to be the one to be invalidated. By moving it to
the end the most a member setter is going to do is free the surface we
don't want anymore.
The GameState subdirectory no longer includes its parent.

That means all the #includes to files in the parent directory need to be
prepended with "../". As they have.
Added a todo to the animation class in the MenuGameState.cpp file.