* string_append_c(): use another name for buf
* imap_roomname():
* 256 is double ROOMNAMELEN; calculate it here to show the relation in place
* extract_token() gives us -1 or the stringlength, use it instead of doing another strlen a line below
* use safestrncpy()
* do_imap_match():
* while lowercasing run till \0 rather than doing strlen above
* respect the size of the target buffer...
* For-loop: assign pointers here, since we start using them here; use IsEmptyStr all over the place (also some forgotten ones...)