Improve the pollen ergonomics

[zainab-ali]

Pollen is a bit difficult to work with. We could improve it by:

• using a better parser (cats-parse?)
• adding a linter to mill
• polishing up the Pollen Emacs mode

It would also be great to improve the decoders to generate a specification for pollen tags.

[zainab-ali]

The Pollen Emacs mode is polished up. It has basic syntax highlighting, although no linting as of yet.