log system rewrite to use sqlite database instead of plain ascii files. this allows us to scale better (be faster), provide search in history, and save logs for JIDs that are non-ASCII. PLEASE read http://trac.gajim.org/wiki/MigrateLogToDot9DB

commit logic of func; we were returning anyways. TC is oftenly touched, so I commit to avoid conflicts

add uniq; fix name of index to be cooler, fix a typo in comment, and most importantly use lastrowid instead of asking max (eg. play a little less with db