Move updated cursor position to the end of whitespace on completion.

If there are extra spaces at the end of the text while doing
autocomplete matching, put the cursor at the end of the string
of spaces, rather than right after the (possibly failed)
completion.

Resolves issue #97.
Allow <server>:<port> syntax optionally for /SERVER command.

This allows both colon-separated (Web standard) and
space-separated (ircII argument standard) server and port
arguments. Includes extended usage message.

Resolves issue #194.
Merge remote branch 'origin/autocomplete_cursor' into tvierling
Merge remote branch 'origin/colon_port' into tvierling