Add new private control 'EditMenu'

This control will be used as a part of the different
text edit controls for controlling how the edit menu
should work.

Change-Id: Id3ed5795111c37269fce62a97cf4d9bde1b5f6b3
Add EditMenu to input controls

Add EditMenu to TextArea, TextField, ComboBox and
SpinBox.

Change-Id: Ic2fed55c467dde65334006d252f4052430f3f40c
update example

Change-Id: Id7abcc298e7b5586f0b328f431feae3ee7015698
TextHandle: disable the handles mousearea when no selection

Otherewise the handle will still be inside the scene, and eat
mouse events, even when not visible. The result will be that
you e.g cannot move the cursor to the place where you left the
handle, since you cannot touch the input field underneath

Change-Id: Id8c436964be1235bb7919f81659d0ead1b2c89df