rename IpfsDHT to DHT

[Stebalien]

(and add a type alias to avoid breaking anything)

Blocked on the pipelining PR (would be painful to rebase again).

[anacrolix]

I would suggest using a word other than DHT. Node, Client, Server, Instance or something like that. This gives consumers of the package a variable naming suggestion other than dht which clashes with the package name. It's also obvious that it's already related to DHT in some way due to the package name. I can redo this PR to implement this if desired.

[vyzo]

I am fine with calling it DHT.

[anacrolix]

Per the Kademlia nomenclature, I think Node is most appropriate. It also avoids naming stutter. DHT is not accurate, and is a generic name for the "main thing" in the package. DHT is the sum of all the nodes operating together, and a name for the technology. What the dht package is providing here is an instance of a node. The consumer of the API wants to write:

dht := dht.NewDHT(...)

But cannot, due to default naming clashes. This kind of thing is very annoying in Go APIs, and results in different users coming up with their own inconsistent variable names.

[anacrolix]

I'm closing this as it's rotting. There's no consensus on renaming yet. See also #223 (comment).