RFC WIP on python / PEG version of planout

Initial python planout compiler

Still todo:
- [ ] JSON literal (or hashmap / dict?)
- [ ] Unit-Tests
- [x] Switch
- [ ] Else
- [ ] Port to JS ?


This PR is mostly for comments rather than as something that is done to be merged.
Thanks for the spot, I will take a look at the grammar to see if I can kill off 1 and fixup 2