Minimize boilerplate with attributes

Simplify syntax to minimize getters, setters, and custom function names; perhaps via @property

• in library .py files:
  • Parameters
  • Composables
• in builder files:
  • Constraints, through a subcomponent property maybe? Probably needs to be different than the parameter property on a subcomponent object. (related to #13)
  • Interfaces?

added enhancementcore label

changed milestone to %0.3.x

marked this issue as related to #27

marked the checklist item Parameters as completed

mentioned in commit caf5d282

mentioned in commit dedba145