* smp protocol: short links types and other changes from RFC
* add fields for queue link ID and data
* create queue and ntf credentials with NEW command
* all tests
* simplfiy types, update rfc
* update rfc
* include SenderId in NEW request in case queue data is sent
* store queue data and generate link ID if needed
* update rfc
* agent API and types
* SMP commands and persistence for short links
* SMP client functions for short links
* agent client functions for short links
* create rcv queue with short link (TODO secret_box)
* encryption and encoding for link data, postgres client migration
* test creating short link
* get link and data, tests
* comments
* type signature