Make TextEdit word selection more natural.

Make TextEdit word selection more natural.

QTextControl will only extend the selection to a word if the cursor is
directly over it which prevents the selection being extended if the
mouse is dragged up or down a to a shorter line of text making it
difficult to select multiple lines of text.  Just disable that
limitation when the TextEdit word selection is enabled.

Change-Id: I3b9d1575c0141db8441197d740de94a90eacc077
Task-number: QTBUG-19230
Reviewed-by: Martin Jones
Reviewed-on: http://codereview.qt.nokia.com/292
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Andrew den Exter <andrew.den-exter@nokia.com>