Added logging to lua callbacks.

  This is part of #95.  I'm wondering if the on_idle callback
 is happening at teh same time as the on_message_parse code is
 running.

  Since we borrow the m_lua member from CLua for the duration
 it is possible we're seeing corruption of the internal state
that way.

  Adding a mutex would help narrow that down; but that means
 pthreads..