Contacts drag-n-drop default action is to move contacts (#1488751)
Added possibility to choose to move or copy contacts from drag-n-drop menu (#1488751)
Use consistent naming: 'moveto' -> 'move'
'moveto' -> 'move', cs fixes
Fix email duplicate check on contact move/copy
Merge branch 'master' of github.com:roundcube/roundcubemail
Fix so setting frame to blank page works also while frame is loading another page