[#595] First class types

[jonhue]

• change default value operator from := to =
• investigate conflict between member_pattern and shorthand_member_pattern
• allow top-level type hints in instances
• specify supertypes, inline options of grammar
• investigate changing function type to => (if changed, also adjust map type)
• generalize type-specific operands
• remove functions from utils; choose more accurate field names
• remove ';' statement terminator, use behavior within blocks for program