Elements integration

[romanz]

Currently there are 3 trezor-firmware PRs relevant for Liquid:

• #317 - adding Python wrappers for blinding & unblinding secp256k1_zkp APIs.

  • It requires increasing the current TREZOR stack size (for rangeproof generation).
  • For testing, it can be done by tweaking the linker script - see integration tests blinding & unblinding Elements' confidential transaction.

• #473 - adding explicit transactions' signature support.

  • It has a few small TODOs (validation-related) - but it can be tested on the emulator/device - see integration tests producing valid Elements' explicit transaction.
  • I think that it's tagged with backlog since they plan to refactor the transaction signature code.

• #474 - adding confidential address generation (via SLIP-0077).

  • I think it is ready to be reviewed - will ping the PR.