dillon1000/react

Make CompilerPipeline a generator

Turns CompilerPipeline into two functions: 

* `run()` is a generator and yields values that are a disjoint union of either 
AST/HIR/ReactiveFunction along with a name for that step. The idea is to use 
this in the playground so that it always matches the exact steps for 
compilation. I'll update playground in a follow-up. 

* `compile()` is ast in, ast out, and uses `run()` under the hood.