Add a SmoothHelper and apply setSmooth to MeterWidget.
Use the SmoothHelper in the NumberWidget.
Increase the period of 'meterSource' in the default configuration.
Minor style fixes. Fix 1080p config.
Rename internal properties of SmoothHelper to avoid collisions with
classes that use the mixin.
Make the default duration of the transition in the 'setSmooth' method of
SmoothHelper a property.
Change meter widget maximum values to showcase the smoothness.
Merge pull request #2 from ShiftForward/smooth-helper

Add a SmoothHelper with the 'setSmooth' method for smooth transitions