Spacing type radio button for repeat and circular repeat node

[Ripper53]

Closes #2551

1. Added Spacing radio parameter to Repeat node, containing Span, Envelope, Pitch, and Gap options for spacing. See issue for how they must be spaced.
2. Added Angle Pitch float parameter and Spacing radio parameter for Circular Repeat node. The Span option uses the calculations which already existed, the Pitch option rotates the next instance around the radius of the imaginary circle according to the Angle Pitch parameter and places the shape there.
3. Added a unit macro attribute. Given string parameter is displayed as a unit type for the parameter.
4. Added a step macro attribute. Given integer parameter is used as the step value for the parameter (ex. the arrow buttons on a number input increment/decrement by step amount).
5. Added a display_decimal_places macro attribute. Given positive integer parameter is used to know how many decimal places to display for the number input if they are not 0.

Usage for macros:

#[unit('px')]
#[step(2.)]
#[display_decimal_places(1)]
num: f64