Format strings 2

Finally check of string formatting.

The calls to vprintf in game.cpp and computer.cpp have been replaced with vstring_format, so it should be save for strings of any length.

Having two versions of *printz seemed confusing, one does need a format string + arguments, the other takes an already formatted string.

I checked the *printz functions and added a default format string if needed. It is technically not always required to write `printz("%s", text.c_str())`, but often the text comes from json and is possibly translated.