fix database typo
ex 4.65 - done
ex 4.66 - done
ex 4.67 - skipped *******
ex 4.68 - done (using prolog)
ex 4.69 - ends in grandson
ex 4.69 - done
qeval - code for driver loop
qeval - instantiate
qeval - eval procedure
qeval - simple queries
qeval - compound queries
qeval - filter
qeval - main file
qeval - find and check assertions
qeval - pattern matching

still no clue WTF I'm writing.
I really hate the style which introduces
important code without any building block given
qeval - rules and unification
qeval - rules and unification 2
qeval - maintaining the database 1
qeval - maintaining the database 2