Support for updating an existing object #197
Description
Is your feature request related to a problem? Please describe.
Support updating existing objects.
Describe the solution you'd like
Construct a new base class ObjectUpdateMappie with the functions updateFrom(source: T, updater: UPDATER): T and updating dsl.
When updating only var properties, do not create a new object but update the existing object.
Additional context
See discussion #191.