Having both selectionChanged and selectionCleared as well as
sendSelection and sendClearSelection complicates things. API users
have to connect to both signals, internally the methods have logic
to call themselves but in the end do the same as the protocols only
know send_selection.
This makes KWin switch to in-tree copy of KWaylandServer codebase.
KWaylandServer namespace has been left as is. It will be addressed later
by renaming classes in order to fit in the KWin namespace.
