Summary

WIP

• adds JsonObject#properties that gives a list of object properties which is extracted from an interface extending JsonObject
• adds JsonValue#as with additional callback function (low level support that allows to extract the properties by observing the calls)

Changes

• object validation uses the new properties method as basis
• object validation bound changed to JsonObject (from JsonAbstractObject)
• typed access (abstract methods support) got packaged into a Access object internally. This reduced the footprint as this is an object that is shared for all views created from the same root