Add a manually written "ping responder" with the new libraries
Error message: we're looking for 'config.ml' not '*.conf'

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Merge pull request #197 from djs55/message

Error message: we're looking for 'config.ml' not '*.conf'
Add types from mirage/mirage-types directly in this repo
Add a mirage-types.lwt subpackage
Integrate the `mirage-types` code into `types`.

This is built as a separate library from the command-line tool, via the
`install-types` Makefile target.
Make the device initialization a generic Failure for now

This avoids exposing a concrete exception value in Mirage-types
Use the mirage-types.lwt packages in generated Makefiles
adapt Makefile for new build scheme (with unified mirage-types)
Fix two examples to open the V1_LWT module types so they compile
Fix case of mirage-types META exists_if
Be more permissive with clean errors
Adapt Basic_ethif to respond to TCP requests
Add TCPV4 module to the V1 types
Adapt TCPv4 type for a listener-based API rather than mutable hooks
Add a buffered CHANNEL module type
Spin up a DHCP example in the basic_ethif stack
Mark a TODO to improve the TCP/IP module type
Improve TCP error reporting interface
TCP: Replace the specific input callback with an abstract type.

This permits the socket and direct backends to drive their input
functions using different signatures.