Debugging tools

[verhoevenv]

Improvements to debugging. This will mostly be about unearthing what already exists, and making it clear and usable in the code. Possible things:

• More fine-grained log files, for example different files/filters for errors, info, debug
• Maybe add timing to the log file?
• Finding out how the frame debug type is supposed to work, can you make the game step one frame?
• FPS counter
• On-screen debugging info
  • Messages on top
  • Messages attached to ingame-objects

I suggest we keep this topic mostly for discussion. Small things can be done ad-hoc. We can open separate issues for the larger things we might want to add.