+(* returns a list of all the equalities in the tree that are in relation
+ "mode" with the given term, where mode can be either Matching or
+ Unification.
+
+ Format of the return value: list of tuples in the form:
+ (position - Left or Right - of the term that matched the given one in this
+ equality,
+ equality found)
+
+ Note that if equality is "left = right", if the ordering is left > right,
+ the position will always be Left, and if the ordering is left < right,
+ position will be Right.
+*)