Support for Java 'generics'.

(In [6432]) Support for java generics. No runtime dynamically defined entities - but support for statically defined subtypes of generic base classes. eg.

@Entity
class Foo<T> {
  T getFoo() {...}
  @Predicate()
  void setFoo(T v) {...}
}

@Entity
class Bar extends Foo<Integer> {
}

Bar b = new Bar();
Foo f = new Foo<Double>();

'b' will be persisted correctly. But 'f' will not since by default getFoo() is supposed to be an rdfs object-property and therefore the insert will fail since a URI is what is expected for the 'foo' property.

Note also that java.util.Collection of generics and arrays of generics are also supported. eg. List<T> getFoos() or T[] getFoos() both are valid generic base class propery types.

T can resolve to any association or literal. However Foo<T> as a return type for getFoo() is not supported. From the example above, the resolved Foo<Integer> is not recognized as Bar in this case. So the generic type variable 'T' will be ignored in this case.

This closes #780.