plugin loading
test plugin sendin 'test' instead of any message
change translation rules for plugins
add Plugins tab to Preferences, a plugin is Check
plugins replace methods not classes
load plugins from torchat.main

plugins must not be loaded each time torchat module
is imported
import plugins without imp module

imp reinitializes module even if it is already loaded
feature test_plugin

*settings item for replacement text
*translations
show plugin name if no description available
conference features as a plugin
import tranlation after plugin import

plugin description are not translated if translation is not imported
russian translate tab title Plugins
Check conference.no_gui
conference !list command
fix update of other buddy's avatar to no avatar

If somebody removed his avatar, this was reflected in
GUI only after GUI restart
many commands in conference plugin

* roles
* mute/kick/etc
* topic, description, avatar
each conference command lives in own function
fix conference.ignore, address in place of buddy
conference members can not ignore moderators
conference doesn't resend messages starting with [