privmsg_prefix should modify outgoing Query buffer messages to be prefixed as well

This is somewhat(very) ugly and unfortunately the nick or host can change between when a message was first sent and when we'll be playing it back.  However this should work most of the time.

I at least tested it and it works when the nick has not changed and the host has (mode +/- x)
It changes
```
"           "
```
to
```
" "
```