What is the approach of RGB architecture?

@UkolovaOlga is already working on this.

Since May 12, 2020.

### RGB uses paradigm-based approach:
* Layer isolation via abstraction
* Layer interaction via strictly-defined interfaces
* No future hardforks, just a single release

### Common development/coding architecture paradigms used for RGB:
* Strict encoding: LNPBP-6
* Single-use seals: LNPBP-7
* Cryptographic commitments: LNPBP-8
* Client-side verification: LNPBP-9
Paradigms descriptions can be found in 
GitHub [here](https://github.com/LNP-BP/rust-lnpbp/tree/refactor-structure/src/paradigms)

### RGB applies these general paradigms to Bitcoin transaction graph
* Single-use seals: transaction output-based seals (LNPBP-10; lnpbp::bp::txo_seals)
* Strict encoding: RGB consensus encoding (LNPBP-11; lnpbp::rgb::*)
* Cryptographic commitments:
- deterministic bitcoin commitments (LNPBP-1, -2, -3; lnpbp::bp::dbc)
- multi-contract commitments (LNPBP-4; lnpbp::lnpbps::lnpbp4)
* Client-side verification:
- RGB schema (LNPBP-12; lnpbp::rgb::schema)
- RGB contracts 
(LNPBP-13; lnpbp::rgb::{transition, stash, ancor, consignment})