Change playposition range back to 0-1. Fixes Bug #1201972.
Fix for hasVinylControl not performing the check correctly.
In other news, default arguments considered harmful.
Merge pull request #220 from rryan/playposition-range

Change playposition range back to 0-1. Fixes Bug #1201972.
Support resizing WSliderComposed.
Eliminate unnecessary widget renders from control changes.

Instead of re-rendering on every control change (via
WWidget::onConnectedControlChanged), check for changes in what we would render
first.

Updated: WDisplay, WKnob, WKnobComposed, WSliderComposed, WStatusLight
Left unchanged: WWaveformViewer, WPushButton, WOverview, WVuMeter