Switch to Qt::PreciseTimer for higher timer precision on Windows.

Using Qt::PreciseTimer for the Delayed Paint Helper improves the drawing framerate by a bit, given that the system can handle it.
If the stabilizerDelayedPaintInterval config is set to below 20, it actually already uses a high precision timer automatically, so this change only affects stabilizerDelayedPaintInterval of a value greater than or equal to 20 (which includes the default value).

Using Qt::PreciseTimer for the Stabilizer Sampler might subtly change the behaviour of the stabilizer due to a decrease in timer activation interval. (Before the change, on my system the timer would activate every 60-or-so ms when stabilizerSampleSize is set to 50.)

I am not quite sure what would happen if the system is weak enough or is heavily loaded, and the performance cannot catch up with the timers.