Also includes general improvements to the slider widget such as an optional
"autotrim" function to cut off trailing zeroes, a "format" string that's easier
to internationalize, and general tidiness.
Cuts down on a lot of duplicate code between
TimelineWidget/ViewerWidget/CurveWidget/NodeParamView
and TimelinePanel/ViewerPanel/CurvePanel/ParamPanel since they all use similar
time functions.
A slider can now hold a float value and display it in the UI converted to
either a percentage or a decibel (still returning a linear float value
programmatically for the rest of the code).
itsmattkc