Implemented a config file parser and added a config file.

The config files name is 'config' and it has to exist in the same
directory as the executable. Of course we could make it possible to set
the filepath via program parameter.
Adapted main.
Put the template member functions of SimpleGUIGame into the header.
Merge branch 'master' of github.com:chaot4/sea-crossing into dev

Conflicts:
	src/main.cpp