- fix inflight status in QUEUE_REMOVE message
- log_warn -> log_warnx
fix issue #201, a ~/.forward file that expands to an empty expand tree
should accept mail as if without expansion.

fix by Naabed, reworked slightly be me
Remove the message size param in m_create().  Instead, remember
the message paramemters on the mproc, and store message data on
an internal auto-growable buffer, then create the full imsg on
m_close().
remove extra parameter in m_create().
put filters in a more or less working state
add support for + in virtual domains