basic operations definitions and negations. Also, removed the negated boolean
Added file unification.py that contains the unification code & implemented separated negate & push_negation for connectives and Quanitifiers
removed using __str__ from all except predicate class
implemented remove_equivalences & remove_implications. More testing would be good
added push nots inwards and some modifications to remove equivalences and remove implications
2 bug fixes
 done with  standardize_apart and added file cnf_tests for other simple tests
changed connectives -> Connective
cleaned some print statements and comments
removed useless lines
used parent class for checking
changed variable to variable_name in quantifiers
used parent class in standardize apart
renamed the convert methods to get_or and get_implication
changed variable to variable_name in standardize apart
removed standardize apart
solved some of the problems associated with copying and added few functions to be used later
Added deepcopy in implications
Added correct print statment for functions
Fixed Standardize apart