Migrate to solidity-parser-antlr about solidity-coverage

[cgewecke]

Differences:

Instantiate w/ options:

let ast = SolidityParserAntlr.parse(contract.source, {range: true});

• EOS is the terminating character of the range
• node.start === node.range[0];
• node.end === node.range[1];
• Program --> SourceUnit w/ children
• Contract --> body === subNodes
• .consequent === .trueBody
• .alternate === .falseBody
• BlockStatement === Block

[cgewecke]

Closing for the time being - if we implement in-memory code execution tracking we'll likely end up using the solc ast because we'll want the source-map and line-column data to come from the same source.