KnobEventHandler should have getters for properties such as range

[sboettner]

Properties such as range, step and usingLog are stored in a private area and no getter methods exist. However, when implementing a custom knob, it may be necessary to have access to this information.

[falkTX]

either that or define a set of usual things needed for parameter sliders, knobs, buttons, etc in a single struct. with the idea that the same data model would be used on dsp and ui side.