Discussion on Standard for composing NFT's metadata

[thomasnft]

This issue is opened for discussion on a Standard for composing NFT's metadata, enable an NFT's metadata is composed of other sources NFT's metadata.
Key points:

1. NFT's owner is able to compose (or decompose) his NFT's metadata, to gain value of NFT.
2. The composition can be done in a permissionless manner.
3. Only NFT's metadata which belongs to the same Dapp is composable.

This issue number will be used as a KIP number.