Refactor setup and adding some flags

this shouldn't change any of the game logic
changes:
- flags to define initial number of doctors, infected, etc and amount of wood (-d, -i, -n, -s and -w)
- defaults to 50x100 if no size or map arguments are supplied
- defaults to 5% doctors and soldiers and 10% nurses and infected without arguments
- during grid generation, doctors, etc. shouldn't overwrite each other anymore (ie they always replace a citizen)
- -h & --help flags to display help
- exit(0) instead of die on win and help