dmq: resolve IP address and store in node structure
dmq: add the following config functions:

- dmq_t_replicate(): Replicates current SIP message to all active DMQ nodes. Includes built-in loop detection which can be skipped with optional parameter.
- dmq_is_from_node(): Checks whether current message has come from another node, based on source IP.
dmq: include resolved IP address in RPC list_nodes output
dmq: update documentation with new functions dmq_t_replicate() and dmq_is_from_node()