TFT<->ERC20 Bridge

[GlenDC]

• adds ERC20 Transactions to TFT;
• adds packages as well as dependencies to support ERC20 interaction (validation, event listening and Tx creation, using a light client);
• adds the bridged cmd that runs a bridge between TFT and ERC20 (TFT20), allowing funds to be transferred between these;
• adds v1.1.2 (alpha) changelog;
• fixed Makefile xc and xc-edge targets, allowing for xc builds using xgo (as to be able to handle the CGO requirements in a XC environment);