refactor(message): ensure NSNumber commands handled, implement static serializing

ARC complains about casting integral types to ids, unfortunately, so it is necessary to wrap
kACX... constants in NSNumbers. ARC did not complain about this previously due to the lack
of tests using the code in that way.

Static serialization is now implemented as a performance helper to avoid some needless
allocation of temporary Message objects. This is intended primarily for use by the
ACXController and its helper send* methods.
feat(controller): begin implementation of network controller infrastructure

The controller is responsible for collecting and deserializing messages from the server, as well as
acting as an interface through which the client or plugins may dispatch messages to the server. It
should also notify the client/plugins when messages are received, so that they may be handled with
minimal code.
chore(xcodeproj): xcodeproj updates for last changes