until we find a way to detect snaps from releases revert a commit I did some weeks ago to assist Yann release .exe faster

 * we now migrate automaticaly at startup in a thread
 * progressDialog now scroll textvew to the end

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

comment get_real_jid_from_fjid to assure future protection from refactoring and add docstring to get return values without reading the code. Both are importnat for such api funcs

better code to handle all these events

file transfer request can now be stored in awaiting_events queue and recalled from roster / filetransfer / popup notification

single messages are well handled: they are saved in awaiting_events if needed and are printed when we dubble click a contact row, or systray or popup window

it now contains subject of messages

refactor to allow changing our nick after nick conflict but first #967 needs to be fixed so I can test