host,pkg/*: Fix compilation issues.

Use pointers as a general rule, including for channel contents.  Revert some dropped directionality hints on chan types.

Finish propagating some new and dangling errors in the area.

Signed-off-by: Eric Myhre <eric@flynn.io>
host: Finish connecting 'attach' to httprouter.

Signed-off-by: Eric Myhre <eric@flynn.io>
host: Use new RemoveJob api.

Signed-off-by: Eric Myhre <eric@flynn.io>