#51: (E)WIF: add four methods: devine format, allow passing to the f() an hexadecimal string
- which will devine if it’s an WIF or an EWIF format.
- allow (E)WIF imports from string parameter in hexadecimal rather than from file.
from_wif_or_ewif_file()from_wif_or_ewif_hex()from_wif_hex()from_ewif_hex()