Make KHangMan run on kf5 based libkeduvocdocument.

Remove Declarative lib since KHangMan doesn't use it.
Rename some member variables to m_*.
Make m_winCount and m_lossCount private.
Make KHangManView update lossCount if newGame is called.
Use QUrl::fromLocalFile to open kvtml files and no longer crash.
Add a check for empty string in paint so we don't crash in cases where kvtml file doesn't open.