Add support for remaining special keywords

[nobodywasishere]

=======================
misc keywords / methods
=======================

super
previous_def
uninitialized Class

---

(source_file
  (identifier)
  (identifier)
  (call
    (identifier)
    (argument_list
      (constant))))

should be something like:

(source_file
  (super)
  (previous_def)
  (uninitialized
    (constant))