Protected enum methods crash

[OscarRodriguezPrieto]

Enum types had no "isFinal" attribute since they are all final.
This caused a crash when there is a protected method inside an enum.
If there is a protected method, to know whether it is accessible from the client, ProgQuery asks the current type definition whether it is final or not, relying on the "isFinal" property of the node stored as the last type definition visited.
Since there was no property, a NullPointerException was raised.
Now, enum types and interfaces both have isFinal and isStatic properties, which they are always (true, false) for enums and (false, false) for interfaces.