Add Musicoin support

[mkrufky]

homepage : https://musicoin.org
block explorer : https://explorer.musicoin.org
slip0044 index : 184
chainId : 7762959

depends-on: trezor/trezor-mcu#388

[prusnak]

Can you please point me to the documentation where Musiccoin claims it is using EIP-155 replay protection and they use chainId = 7762959?

[mkrufky]

Musicoin has been unable to work with hardware wallets until the following PR was merged recently:
trezor/trezor-mcu#381

The Musicoin network has had EIP-155 Replay attack protection enabled on their network ever since the following PR got merged in February:
Musicoin/go-musicoin#62

Observe the Chain ID of 7762959 in the same PR, here:
https://github.com/Musicoin/go-musicoin/pull/62/files#diff-a894bbf771e5541f902b5b16f367f99dL37

Some additional links showing Musicoin's Chain ID of 7762959:

Bitcointalk:
https://bitcointalk.org/index.php?topic=1776113.0

Steemit - Musicoin Specification:
https://steemit.com/bitcoin/@animelovers/musicoin-altcoin-nuanced-music-2017712t164413659z

StackExchange:
https://ethereum.stackexchange.com/questions/17051/how-to-select-a-network-id-or-is-there-a-list-of-network-ids

[matejcik]

@mkrufky your trezor-common PR claims that the shortcut is MUSIC, yet your trezor-mcu PR uses MUSI suffix. Which is it?