Rework tests to combine atomic and xmr test cases.
Modify btc interface to support P2WSH_nested_in_BIP16_P2SH
Add coin feature tests to test_btc_xmr.py
Only the upgradetohd command sets the hdseed
upgradetohd can only run once the chain is synced
Basicswap stores the hash of the root_key in it's db to check for the expected seed.
Prefer not to store the real key.