[cl-compatible] Fix assoc :key and add *-if *-if-not functions

[Affonso-Gui]

1. Fix :key behaviour in assoc.

eus$ (assoc 3 '((1 . "one") (2 . "two") (3 . "three")) :key #'print)
(1 . "one")
(2 . "two")
(3 . "three")
;; nil

sbcl$ (assoc 3 '((1 . "one") (2 . "two") (3 . "three")) :key #'print)
1 
2 
3 
;; (3 . "three")

2. Add :key :test :test-not key-parameters to rassoc.

3. Implement assoc-if, assoc-if-not, rassoc-if, rassoc-if-not.

4. Move superassoc and supermember to system::raw-assoc and system::raw-member, as in sequences.c.

Chart for assoc and rassoc tests:

Situation	Results
before changes	55/104
with changes	80/104
with changes and eus-* auxiliary	91/104
including -if and -if-not tests	170/209