[PROJ] idea: projection metadata

[Nyall Dawson]

Hi list,

Just wanted to bounce an idea I had recently. I'd love to see proj
gain an API for querying projection metadata, specifically:

- retrieve a list of all available projection methods
- given a a projection, retrieve the description, classification,
available forms, defined area, etc metadata listed at the top of
projection documentation page
- given a projection, retrieve a list of parameters and their
descriptions, optionality, and default value

Does this sound like a desirable inclusion in the proj API? I'm
willing to chip away at this in spare time, but would love some
pointers on a recommended approach to take to implement it...

Nyall