QTimer on Windows uses excessive power for timers

I discovered this issue after looking at the Quassel bug tracker, and saw Bug #1521: Quassel requests 1ms timer precision on Windows client - Quassel IRC - Quassel IRC Issue Tracker (quassel-irc.org); the issue is that when creating a QTimer, even at coarse resolution, the system timer created is high resolution and is unnecessarily power-hungry, especially on mobile devices.

While precision timers should retain the call to SetTimer when unable to use multimedia timers, Qt::CoarseTimer and Qt::VeryCoarseTimer should instead use SetCoalescableTimer, which offers similar guarantees to the existing descriptions of coarse and very coarse timers, but will be significantly more efficient. A document linked in the description of uToleranceDelay describes the benefits that come from using coalescing timers; this will have a significant impact on all timer users.