added in unittests ;)

fixed some bugs in unregistration

added some consistent behavior to 
discovery errors (not finding a listener,
 listener method, or filter) so that
all of them will stop publishing and
raise the error

fixed bug where the event channel txn publishing
limit exception would get swallowed if all the
publishing was on the same event type.

added in event mapping, for mapping one event type
on to multiple event types.

cleaned up the source code, lint style

removed the external method for filter functionality

added in callable check for filters and methods

massively reworked management interfaces so that the zmi
is useful for manipulating the channel 

allowed listener methods to be context acquired (registration 
previously prevented this).