Support for Trezor Model T & on-device passphrase entry

[gkaindl]

Following up on #99, I managed to get the Trezor Model T to work with Etherwall. I've tested importing the first 5 public keys, entering a passphrase on-device and via the app, as well as signing a transaction.

The following caveats apply:

• The code is a bit rough, I'm afraid.
• I don't have a Trezor One, so I couldn't test whether I broke anything with the HID-based protocol.
• I don't know how to detect a Trezor One running the newer USB based protocol, once it gets enabled there. Right now, all device detection works via VID/PID. I suppose one way to try would be to send a HID-based Initialize message and check for valid data, then switch to the USB-based protocol if that returns garbage data. I didn't implement this, though.
• When you are asked to enter a passphrase, the red-ish overlay calls the action you are doing on your trezor "undefined". I couldn't figure out how to address this... :-(
• I've kept the ability to do debug output of the transfer contents in wire.cpp in, disabled through an ifdef. I suppose this can be removed, though it might prove useful if problems are found with the new or old transfer protocol.
• I've also had to adapt the logic in trezor.cpp a bit – The Model T enables you to enter the passphrase on-device, which uses a (new) PassphraseStateRequest when entry is finished. I couldn't figure out exactly how this is supposed to work, but apparently, just sending back a PassphraseStateAck is enough to make it work, since the device (or host) can't figure out anyway if you entered the "correct" passphrase, e.g. the one you intended to use.
• I've built this on OS X 10.13, so I adapted Etherwall.pro to point to the 10.13 SDK – You will probably want to revert this back to 10.12 if that's what you're using for the builds.
• I've also added a static version of libusb-1.0 in Etherwall.pro as a build dependency. I'm using the version provided by Homebrew.

[almindor]

Ah good to know. Thanks for all the work!

One more thing. I'm going to need you to sign your commits. You can maybe do it more easily by re-PR-ing from scratch using this code. See here on how to do it.

Etherwall is locked to only accept signed commits, which includes PR merges.

[almindor]

Closing since we've got #101 now