GitLab

cleaner command completion/calling

handle both cmdkit.Error and *cmdkit.Error in ChanResponse

**Returning errors/calling:**

Instead of having a dance where we:
  * Close the response emitter immediately if the command succeeds.
  * Return an error, call SetError, and then close the response emitter if it
    fails.

Just set the error from within the `Call` command and always close the response
emitter.

**Doner**

Get rid of the Done channel/doner interface from the response emitter. We close
the response emitter after finishing the Call *anyways* so this channel isn't
necessary (anymore, at least).

fixes https://github.com/ipfs/go-ipfs/issues/4683

Better arrays

testing

Don't handle timeouts in Execute.

Instead, handle it at the boundaries (in ServeHTTP and the CLI's Run function).
This ensures that we actually *wait* to finish writing everything before
canceling the context.

always cancel the request context when calling reqCancel

First check for HEAD request, then error out if writer is nil

Also, fix a nil pointer error.

[RFC] don't generate a stack trace for every command

use reflection to make writing commands nicer

We can add these back if we need them but, at the very least, we shouldn't be
unconditionally generating stack traces on `Close`.

Blocked - Changes for cmds 1.0

It's slow and this code isn't platform dependent.

fixes #42

We *always* expect environments to be able to return a context so we might as
well enforce this with the type system.

These aren't placeholder contexts.