Small miscellaneous fixes

This PR contains small fixes I made to PokittoLib during the development of PokittoGP.

Files and directories can be read from a specified path in the simulator and HW.
Small fixes to the on-screen FPS counter and Pokitto Crash Screen.
Improved error handling in BmpImage.cpp.
Made patch and block count in the synth to be configurable.
Improved mode 13 code in the simulator.

pokitto / PokittoLib