ecdsa 0.13.3

Fix CVE-2019-14853 - possible DoS caused by malformed signature decoding
Fix CVE-2019-14859 - signature malleability caused by insufficient checks of DER encoding

Also harden key decoding from string and DER encodings.

ecdsa 0.13.2

Restore compatibility of setup.py with Python 2.6 and 2.7.

ecdsa 0.13.1

Fix the PyPI wheel - the old version included .pyc files.

ecdsa 0.13

Fix the argument order for Curve constructor (put openssl_name= at the end,
with a default value) to unbreak compatibility with external callers who used
the 0.11 convention.

ecdsa 0.12

Switch to Versioneer for version-string management (fixing the broken
ecdsa.__version__ attribute). Add Curve.openssl_name property. Mention
secp256k1 in README, test against OpenSSL. Produce "wheel" distributions. Add
py3.4 and pypy3 compatibility testing. Other minor fixes.