Enforces Array input for deterministicGenerateK
Updates README.md

Adds a larger warning to the stability of the master branch; and updates the library description to be more accurate.
Fixes typo and adds more direct answer
Adds BI.toPaddedBuffer and toBuffer
Removes toPaddedBuffer and extends toBuffer
Adds RFC6979 test vectors and fixes ecdsa.sign/detGenK
WIP