Refactor QMouseEvent to contain the position inside the window

Refactor QMouseEvent to contain the position inside the window

Rename the default accessors for positions to localPos, windowPos
and screenPos, to be explicit about their use.
Introduce a QT_NO_INTEGER_EVENT_COORDINATES define so one can make sure
to always use the float based coordinates.
Fixup all Qt code to use the correct constructor that specifies all
three coordinates.

Change-Id: If4bb93b8d1e2eb2440260d99680c468706cfe68f
Reviewed-on: http://codereview.qt.nokia.com/4058
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@nokia.com>