The processor parameter values are displayed with two decimal places by
default. However, when these values become very large and exceed about 7
text symbols, the text is too long to fit the label and it'll simply not
show up. This commit fixes that by disabling the decimal place for such
large values, which allows us to show values up to 9,999,999, be it
only at integer precision.
This is the first step in transitioning Piano to a full LibDSP backend.
For now, the delay effect is replaced with a (mostly identical)
implementation in LibDSP.
The new ProcessorParameterSlider attaches to a LibDSP::Processor's
range parameter (LibDSP::ProcessorRangeParameter) and changes it
automatically. It also has the ability to update an external GUI::Label.
This is used for the three delay parameters and it will become useful
for auto-generating UI for Processors.
