Nuke imcb_clean_handle(), which was merging handles accidentally
Well, just deprecated and turned into a no-op. It was only used for
jabber anonymous MUCs, but this is something the IRC layer must take
care of. It stripped all whitespace, control and non-ascii characters,
breaking utf8 nicks support and accidentally merging contacts whose
cleaned-up handles were the same string.
For example, you could have two users with nicks ' ' and ' ' (one and
two spaces respectively) and imcb_clean_handle() would just merge them
into a single handle, , which makes them look like a single irc user.
The same thing happens with nicks that are entirely made of utf8.
Thanks to schoppenhauer from #bitlbee for reporting this and preparing a
test case channel!
