0.36.0

• Implement Interval type, value and ast node.
• Fix token position after consuming comments.
• Add support for interval +, -, * and /operators.
• Add support for interval = and != operators.
• Add support for interval >, >=, < and <= operators.
• Check that interval value in range -170M to 170M.
• Add support for + and - operator between Date and Int.
• Implement justify_days, justify_hours interval functions.