Add Qt::TimerType and the QTimer::timerType property

Add Qt::TimerType and the QTimer::timerType property

The timer type will control the accuracy of the timer. By default, all
timers are CoarseTimers, which allows for +/- 5% interval adjustment.
PreciseTimers will not have any interval adjustments, VeryCoarseTimers
will have intervals adjusted to full second resolution.

Use QTimer::setTimerType() or the QTimer::singleShot() overload to
specify the type.

QObject::startTimer() now takes a Qt::TimerType argument which defaults
to Qt::CoarseTimer. QBasicTimer::startTimer() gets an overload that
takes a Qt::TimerType argument. The argument is unused for now, since
the QAbstractEventDispatcher interface needs to change (done in a
separate commit).

Author: Thiago Macieira <thiago.macieira@nokia.com>
Change-Id: I3100da5aa1fe17ec30b8644897d0fe6ec4a07f52
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>