Travis CI used old cache and did not find the compilation
errors (instead it that errors has been found by us).
Also get rid of some Qt private parts, more fwd decls and so on.
Use Qt::Dialog instead of Qt::Tool which works better with window
activation / deactivation handling.
Stop displaying the panel on all spaces when the call is established.
Also implement panels that appear in all spaces on macOS.
Using them for calls panels and custom notifications, so it
will be possible to use custom notifications in macOS as well.
What has been done:
* Removed deprecated Encoding key
* Specified correct WM class for StartupWMClass key
* Fixed icon name
I also fixed restarting when language is changed and there is no Updater
Signed-off-by: Nicholas Guriev <guriev-ns@ya.ru> (github: mymedia2)