Added: 'loop over a variable' parsing
Added: Interpreter initial commit. Loads nodes. Nodes have validate and eval method.
Added: position data to all AST nodes generated by the parser
Refactor: move 'atom' helper method outside of parser directory, since interpreter test can use it as well
Modified: 'value' property in the AST node for variable, renamed to 'name'. This makes more sense; it represent's the "variable's name"
Added: type information to variable AST node
Added: value type to literal:number
Added: valueType for literal:string
Refactor: Simplify AST node produced for comparison. Remove the node produced for operator. Store operator as a raw value in the comparison's AST node.
Added: valueType for negated expressions
Modified: valueType of the index variable in a loop to be 'number'
Added: valueType for operation nodes
Added: validation for the 'compare' node
Added: support for operations to be part of the condition in if-statements.
Improved: Comparison node validation test.