So you want to add a layer?
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Yay! go add it to the leaflet-providers.js as long as it follows the following
rules:

- Don't violate a providers TOS (if it exists, include a link to it)
- Don't pre-populate api keys with working keys.
- It should be a basic tile source, no exteral libraries etc.
- The owner hasn't asked us to remove it (hasn't happened yet)
