Make apostrophe (') the default hardened marker, as this is more common default option
Remove unnecessary path length checks (removed in the spec, too)
Improve error checks in BIP32Template() direct instantiation
Improve test coverage
Use 'h' as default for hardened_marker argument of BIP32Template.__init__()
Add BIP32Template.from_path() classmethod to create BIP32Template from an
iterable of integers
Initial release