protobuf-c-rpc (0.1) UNRELEASED

 * This is protobuf-c-rpc, which has been split out from protobuf-c.

 * Add protobuf_c_rpc_server_configure_threading().

 * rpc: Rename AF_LOCAL to AF_UNIX (Issue #86, #100).

 * rpc: Handle server responses with NULL messages on the client side
   (Issue #78).

 * rpc: Free the timer created by autoreconnect in case the client has
   failed to connect (Issue #70).

 * Bugs in dsk-dispatch (Issue #65 for one thing; POLLHUP for another; and
   a problem where we moved fd_map into a local variable, when in fact in
   can be reallocated all over the place, in dsk_dispatch_dispatch()).

 * Split the RPC code into client and server parts for clarity.

 * Implement custom RPC protocol API. Use protobuf_c_rpc_client_set_rpc_protocol
   and protobuf_c_rpc_server_set_rpc_protocol to set the custom (de)serializers.
   The default RPC protocol remains the same as before.