fix

plugin_mgr restarts after crash and works.
changed a bit the api for the plugins

short_description has been replaced by help. name can be none to
indicate that the plugin shouldn't be in the plugin list displayed when
"help" is called.
Refactored search in two modules, one for google and one for wikipedia.
compiled regex in google.erl
misc fix
help for a specific plugin

!bot help <plugin_name> prints help for the plugin.
renamed file

plugin_api --> irc_api
changed after the api
typo