Gateway Server

replaced H
moved internal errors into function.
Signed-off-by: Simon Kirkby <tigger@interthingy.com>

adds
 trailing slash redirection
 index.html return
 templated directory listing

Signed off : Simon Kirkby <tigger@interthingy.com>

ds-query + ipfs refs local

the prefix should be as short as possible, as this is a
per-block overhead.

@mappum would this work?

cc @mappum can we do this for the copyChunks case?

using Header().Set after WriteHeader() has no effect.
cc @mappum

Queries now can be cancelled and the resources collected

ipfs blocks local returns _all_ local refs. For now this is one
long op. future commits will make it async.

fix listener problems

peerstream would hang when it got many temporary errors.
temp errors should not count as an error. Now, it will
only exit when an error is not temporary.

I kept the acceptErr channel because it will no longer
cause a bad hang. The goroutine is exiting, so if it
blocks until acceptErr is read, it's fine. If users
launch tons of listers and see goroutines building up,
they know they should be reading + logging those.

Instead of erroring out, which would break the listener,
we instead log a message and continue. This is not an error,
the internet is a place with lots of probing + connection
failures.

This should handle early breakages, where a failing connection
would take out the listener entirely.

There are probably other errors we should be handling here,
like secure connection failures.

refactor(core): NewIPFSNode constructor