v1.6

Features

• Add support for user defined classes using SerializableType and SerializationStrategy interfaces located in the new mashumaro.types module
• Add new RoundedDecimal class for the decimals with specified precision

Other changes

• Change base class of MissingField from Exception to LookupError
• Change base class of UnserializableDataError from Exception to TypeError
• Raise UnserializableDataError exception for weird types of fields
• Speed to_dict and from_dict methods up to 40% in some cases