[REQ] Add Segwit Sign/Verify support

[brianddk]

Bitcoin issue 10542 discusses how to expand the current sign/verify functionality to include Segwit.

The basic idea is to expand the header byte to help identify the segwit address scheme

35-38 p2sh segwit pubkey (base58)
39-42 segwit pubkey (bech32)

The Trezor FW has already implemented this in commit b5f9a5

As bitcoin core is likely to implement this and Trezor already has, it would be useful to have it implemented in a block explorer too.

[EvilJordan]

Looks like you were wrong about bitcoin core being likely to implement. They don't seem to care.