[FEATURE] implement support for type inheritance

[davidnich]

details:

• child types extend parent types - cannot change parent but only extend parent
• child types can only have one single parent type - no multiple type inheritance
• child types are automatically compatible with parent types
• server and user types should be extensible / inheritable

if we can do this, then we can get rid of many types supplied by modules and just use user types. Currently we have module-supplied types in the building-blocks repo just to extend existing types.