Make it easier to select words at the start of a line.

Make it easier to select words at the start of a line.

QTextControl's word selection will only include a word if the cursor
position is past the mid point of the word. This can make it
difficult to select words near the edges of the screen on touch
devices.  For the TextEdit word selection mode select a word ignore
the relative position within a word.

Task-number: QT-5206
Change-Id: I4e5675596cd89934b3c2bc5d825088887c222fe8
Reviewed-by: Martin Jones
Reviewed-on: http://codereview.qt.nokia.com/4166
Reviewed-by: Andrew den Exter <andrew.den-exter@nokia.com>