processing view intents before saved instance caused troubles when the activity was destroyed
fixes #1969

Conversations only allows correction of the *last* message. so nudging a message into oblivion by adding a message correction doesn't work. also conversations checks the fingerprint for encrypted messages

now that file params has more work to do we should make sure we always call it from a sperate thread

Conversations and Gajim both have an implementation bug that sends the jingle session id instead of the transport id (compare XEP-260 2.2). This commit has a work around for this that remains buggy when using ft:3. If gajim is ever to fix this we will be incompatbile. gajim should implement ft:4 instead. (gajim to gajim is broken as well)