PM handling, challenging the user, manual searching

Also added a 'master' option in the config file: this is essentially a
'whitelist' for the PM commands right now, but could be used for
debugging other features. Fixed up a couple of the trash-talk lines too.
Merge branch 'master' into develop

Conflicts:
	src/mjbot/parse.clj
smh @ conflicts
Moving start-search into core
Merge pull request #2 from ScottehMax/develop

PM handling, user challenging, manual search starting