ABI 1.1 support

This release supports ABI 1.1.

ABI 1.1 was introduced in https://github.com/EOSIO/eos/releases/tag/v1.3.0; it supports these new features:

• Variants: These are values which support multiple types. See EOSIO/eos#5599 for details.
• Binary extensions: These support extending existing rows and actions with new fields. See EOSIO/eos#5600 for details.

Alpha-02

Fixed copyright headers

Alpha-01

First alpha release