Fixes and behavior changes to ircop plugin

ircop changes:
* Now buffers both mode and non-mode requests and processes them
  correctly.
* Added more info to the class docstring on how to use it
* Lots of cleanup / simplification

Other changes:
* non_reentrant() decorator bug fixed.
* non_reentrant() decorator re-organized/cleaned a bit
* admin plugin's ban function fixed to submit both kick and ban requests
  simultaneously