This function was written for already validated UTF-8 but not for text that can be mixed with ISO-8859-1.
To handle that properly it needs to do a bit more validation to avoid mangling its output and instead reject invalid input.
This was broken by several small unicode-incompatible code fragments.
This commit also removes the input limit for the player name and the savegame description. With multibyte encoding, limiting them to a fixed length did not work right.
Currently these will just overflow the fields if the text becomes too long, this needs some additional work.
