Signature verification, fix keypair constructor, cleanup.

Ah. So I wanted bytes initialized fromHex on purpose. From there, I see the code is read as:
* initialize bytes from hex
* there will be 5 tests (up to 255)
* Increment m until tests reaches 0
* at each increment, perform test

Incrementing m within the control statement explicitly couples the logic; inside the loop, this would be an assumption rather than explicit.