Ensure the TextEdit cursor delegate is repositioned on mouse events.

Ensure the TextEdit cursor delegate is repositioned on mouse events.

Update the micro focus when a mouse press changes the cursor position
of a read only TextEdit.

Change-Id: I11855037f7938b2cd23ac6ad165722b5289b4f46
Task-number: QTBUG-19109
Reviewed-by: Martin Jones
Reviewed-on: http://codereview.qt.nokia.com/291
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Andrew den Exter <andrew.den-exter@nokia.com>