This makes `LATIN SMALL LETTER L` confusable with `LATIN SMALL LETTER I`
because `CYRILLIC SMALL LETTER PALOCHKA` "ӏ" (mapping to i) wasn't
confusable with `LATIN SMALL LETTER L` "l" (mapping to l) before.
Also add tests for `str_utf8_comp_confusable`.
`str_utf8_isspace` now returns true if the passed code point renders as
a space, instead of when not.
Add `str_utf8_trim_right`, use this function and
`str_utf8_skip_whitespaces` in the server.
Add tests for the three functions
This uses the Unicode confusable data together with judging how close
two strings are by using the Levenshtein distance.
Adds the commands `name_ban`, `name_unban` and `name_bans`. Kicks
players who join using a banned name and doesn't allow ingame players to
change their names to the banned ones.
