Added utilities to Pair. One is a very simple factory, of(left, right) that creates a new Pair with inferred generic types. The second is a set of similar methods, leftRange(range, right) and rightRange(left, range) that create a list of Pairs where one element stays constant and the other one ranges from one integer to another.
Fixed oversight in intSeq() that created a sequence of [1,9] regardless of what the user supplied as endpoints. Now responds to supplied endpoints appropriately.