show only once unread messages at startup when we have twice the same contact in 2 accounts. Fixes #2921

OS X support is still maintained in the osx_newbuildsys branch - and
only there.

don't require libdbus-1-dev to have gajim-remote. All distribution have libdbus > 0.60 now. Fizes #2992

allow ignore_unknown_contacts, send_os_info and log_encrypted_sessions to be set per_account in ACE. Fixes #4730

He already promised he'll do icons for each activity! ;)

* configure --help to show disable message when --disable-FEATURES (we can use disable or enable
for each one AFAIK)
* Add dbus compile time requirement to README.html

launch. This is necessary because with a big history get_last_date_that_has_logs
can take about 5 seconds on first launch.
Created new gajim subversion.