Add options to the 'Repeat' node for the spacing with envelope/span/pitch/gap

[jennjwang]

We currently implement the Repeat node based on the "span" method of distributing spacing (this should remain the default). A radio button should be added to pick other methods:

• envelope = span + W
• span = (N - 1) * pitch
• pitch
• gap = pitch - W

The Circular Repeat node should also be given new options for min and max angle (without being limited to a total of 360°) and an angular equivalent to span and pitch (I don't think envelope and gap make sense in the angular context— essentially polar coordinates?).