General improvements to tile creator

[bsherin]

• [ ] improve the options editor

  • Insert new option after the currently selected option

• [ ] access to init?

• [ ] allow nested classes

• [ ] allow class variables

[bsherin]

A possible use case to support:

• Case in which the choices for one option affect choices for the others
• A difficult variant of this: Selection of a collection in one option, then selecting from that collection’s columns in another option.

See new idea: run-time options

[bsherin]

I think the comment above doesn't belong here. It's not primarily about the design of the tile creator. It's about dynamic options