Send a request (which we can't handle yet) :-)

Regards #660

MAM messages don't have a type nor a from.
If we detect a message without type let's log it and exit without
continuing to try to parse it.

Otherwise we go into _handle_chat() and crash on the no from.

Let's not crash :-)

Is usefult in many cases if we want cleaner code.
Hope this edit didn't break anything though ;-)

Later we will have several options.
Getting everything since last timestamp (if none everything at all).
Getting everything since today + configure time (1 week).

Should also have a reload all command like conversations once you
cleared the history.

All MAM messages should be written into sql db.
And then probably displayed from there so that regular history works
too.

Only when we start the conversation.
Not yet when we get messaged and a new window is opened.
Need to have sorting of messages in the window buffer then, I guess.
Also MAM IQ should only be send one time in such a case.

If MAM is enabled history from sql backend will not be shown.

`mam` in profrc enables experimental MAM.
Can change soon again. Don't rely on stuff in this stage ;)

g_date_time_add_days() actually creates a new one.