updated ecdsa to >=0.19.1,<0.20.0

updated to v0.7.1

updated to 0.7.0 for block functionality

fixed deserialization of Script object for >75 bytes; issue #68

tag v0.6.6

fixed coinbase input issue with from_raw

updated all files with type hints plus minor updates

updated examples' section

updated README with hdwallet lib and example

updated version