use better names for Ranges in SlitsControlPanel

[pixelzoom]

Related to code review #259, and #279.

SlitsControlPanel has some inadequate names for Ranges.

These are Ranges for slit width, and should be renamed to indicate that, e.g. waterSlitWidthRange.

const waterRange = new Range( 0.5, 2.5 ); // cm
const soundRange = new Range( 20, 160 );
const lightRange = new Range( 200, 1600 );

These are Ranges for slit separation. Consider renaming to (e.g) waterSlitSeparationRange.

const waterSeparationRange = new Range( 1, 5 );
const soundSeparationRange = new Range( 40, 320 ); // cm
const soundSeparationRange = new Range( 40, 320 ); // cm
const lightSeparationRange = new Range( 400, 3200 );

[samreid]

In #279 the slit width ranges were moved to the model, and now appear like this (e.g.,):

slitWidthRange: new Range( 0.5, 2.5 ), // cm

and

sourceSeparationRange: new Range( 1, 5 ), // cm

Please review.

[pixelzoom]

👍 Closing.