Unicode support

You can now use additional characters, outside Latin-1 (ISO 8859-1) with some commands in the game:

• communication commands such as say, tell, and narrate
• info <format>
• board commands such as write and reply

Commands that do not handle these "extended" characters will complain about "unsupported characters".

If you do not want to receive non-ASCII or non-Latin-1 characters, you can now set change charset ascii or change charset latin-1 idependently of which encoding your client/mapper receives.

To change the latter, you "still" use change encoding ascii|latin-1|utf-8. This is only necessary and possible for legacy clients who do not otherwise negotiate which character encoding to use.

All Unicode characters (code points) are not supported; non-Latin scripts are not, for example.

It's far from unlikely that this broke something. Please report any bugs using the bug command!