List of places to convert to TypeScript

[zepumph]

From phetsims/tasks#987, if we end up going with TypeScript, @samreid and I though that it may be nice to have a list of places on the project that could be improved upon.

• UtteranceQueue's constructor parameter should implement an Announcer interface.
• Property and Emitter should be an interface. (for example instead of instanceof checks like https://github.com/phetsims/axon/blob/d848101bd6e9f29d49173b5f41e8a5c7baa70516/js/NumberProperty.js#L82
• Property should have a parametric, generic implementation. Axon has a typescript branch with Property<T> in branch: typescript axon#360
• Re-evaluate the large number of features packed in Node.js (a single file), and see if they can be split up like done in ParallelDOM.js (see Should ParallelDOM be moved into Node? scenery#1159). For example named options.

[samreid]

@zepumph do you still see value in this issue?

[zepumph]

Nah, though it served its purpose.