Now the background of boxes is separated to another widget.
This will allow to use a special layer widget (like settings)
together with the usual layers-boxes upon it, moving the special
widget behind the dark background when a usual layer-box is shown.
Sticker with reply layout fixed. Report box title corrected.
Elided text display sometimes didn't restore last block, fixed.
Removed non-existent class diagram file from MSVC project.
