Removed some error-inducing remnants of accidentally-commited code.
PaddleInput ABC and implementations are now separated into a couple of files.

The PaddleInput ABC can now be found in src/client/PaddleInput.h.
The implementations (MouseInput and the new TestingAI) can now be found
in src/client/input_impls.(h|cpp).

The TestingAI is now used for the top paddle in the PaddleGameState.
Added a simple logging function that outputs a timestamp, severity and a message.
Basic construction and destruction of the LocalServer class is now being logged.
The PaddleGameState now exits without using the crash function.
FPS is now recorded in the game struct rather than spat onto stdout.
Removed some old code referencing some replay functionality I never implemented.
Functions in client/render.h are now implemented in the new client/render.cpp file.
Added a new render_debug function that renders the recored game fps.
Added a flag to the Game structure and command line option to render fps on-screen.