[RGB20] Fungible assets review & discussions

[dr-orlovsky]

This is a place to review & discuss RGB20 (LNPBP-20) standard for fungible assets.

Previous discussions took place in:

• RGB-20 Schema review #70
• Rewrite RGB20 spec using Contractum & concept of interfaces #136
• Accountable pruning procedure for fungible assets schema (RGB-20) #27
• Possible proofs for fungible assets pruning in RGB-20 #28
• Use reissue/replacement RGB schema for asset recovery #50