Is domain sharding still necessary?

[prushforth]

OpenStreetMap is recommending that a,b,c subdomains be removed, replaced with tile.openstreetmap.org.

In light of this, maybe the shard attribute and associated markup is no longer a requirement, and can be dropped.

Adding a to-do list of places this can be removed:

• [x] MapML spec
• [ ] GeoServer MapML extension module code
• [x] Web-Map-Custom-Element
• [x] Experiments
• [x] Web-Map-Doc

[Malvoz]

Since HTTP2 supports unlimited concurrent requests and HTTP2 is supported in all major browsers it does seems that domain sharding is no longer necessary.

[prushforth]

Kind of frustrating that HTTP and support by browsers is progressing faster than this proposal. That said, it's always a pleasure to delete code.