Added a block kind for an interface.

Signed-off-by: Dimitar Dobrev <dpldobrev@yahoo.com>
Reused the method for generating a string representation of an access qualifier.

Signed-off-by: Dimitar Dobrev <dpldobrev@yahoo.com>
Stored the original class in its interface replacement used with multiple inheritance.

Signed-off-by: Dimitar Dobrev <dpldobrev@yahoo.com>