OT_ME: merge called function into create_nym()
opentxs-client: remove load_or_retrieve_signing_key()
OT_ME: merge called function into deposit_cheque()
Merge pull request #496 from toxeus/apiMerge

OT_ME: merge called functions into caller
OT_ME: merge called function into withdraw_voucher()
OT_ME: merge called function into withdraw_cash()
OT_ME: merge called function into trigger_clause()
Merge pull request #499 from toxeus/apiMerge

OT_ME: merge called functions into caller
Removed unused message buffers in connection.
Removed linking to ZMQ in ext and added it for client and server libraries.