No need to represent DTMF with an enum

Status bar update is not done in a separate thread anymore, so the mutex
should not have been there.

This reverts commit a4256fcb, reversing
changes made to aa2dd717.

Conflicts:
	daemon/src/managerimpl.cpp

Signed-off-by: Emmanuel Milou <emmanuel.milou@savoirfairelinux.com>

Assumes that this is the case if a call is ringing when it is
terminated.

Fixed whitespace, removed unused methods, corrected documentation.

Resolved Conflicts:
	daemon/src/managerimpl.cpp

Whenever we hangup or our peer hangs up a call, an entry is added to the history
(in memory). When the daemon exits, it will save the history
automatically.

It only does it once, when saving it (at exit).

This way we only have one representation of the history in memory
instead of 2, and we don't need a ConfigTree for this, standard streams are
sufficient.

We were inserting elements into the toolbar at invalid positions.
Now the indices have been corrected and an assertion added to make
this sort of error more obvious in the future.