considering to change name module and core

[JaeseungYeom]

core can be split into core and client.
module could be server
I have dyad_ctx.{h|c} which only deals with the initialization and finalization of dyad_ctx_t singleton object.
This can remain in core and the rest of consumer and producer can move to client

[ilumsden]

The core/client split is done by #120