Adding a ForStatement solidity AST Node.

- Adding ForStatement node
- Implemented Parsing for ForStatement
- A simple parsing test for the ForStatement
- Work in progress
new ForStatement parsing test and small grammar fix
Solidity ForStatements expressions are now optional
ForStatement typecheck and initExpression is a Statement
Minor issues, grammar update, new ForStatement test
Solidity ForStatement Compiler part

- Work in progress
Solidity: More tests for the ForStatement
Moving comment to function body
Merge pull request #626 from LefterisJP/sol_forStatement

ForStatement for Solidity