Add jagged array support

• 37bd8c7: Add support for jagged arrays of Unity and User types
• 094eb9b: Fix drawing of user type on public fields so that they don't all appear as UdonBehaviour
• e3773f6: Fix implicit numeric conversion from sbyte to float, reported by AirGamer
• 8eb0346: Add error message for attempting to assign to a user type in a field initializer since the incorrect value type will be assigned.
• cf6d97d: Fix null reference exception on newly created programs