Generics migration (#237)

* Generics migration

This attempts to migrate this library in the least invasive way by preserving as
much of the original API as possible. It does not change the tests in a
meaningful way nor does it attempt to upgrade any logic that can be simplified
or improved with generics. This is purely an API migration, and still requires a
lot of additional work to be fully ready.

* Fix a few broken tests around serialization

* Add v2 suffix

* Temporarily change mod name for testing

* Rename module to /v2

examples/priorityqueue/priorityqueue.go

@@ -5,8 +5,9 @@
 package main
 
 import (
-	pq "github.com/emirpasic/gods/queues/priorityqueue"
-	"github.com/emirpasic/gods/utils"
+	"cmp"
+
+	pq "github.com/emirpasic/gods/v2/queues/priorityqueue"
 )
 
 // Element is an entry in the priority queue
@@ -16,10 +17,8 @@ type Element struct {
 }
 
 // Comparator function (sort by element's priority value in descending order)
-func byPriority(a, b interface{}) int {
-	priorityA := a.(Element).priority
-	priorityB := b.(Element).priority
-	return -utils.IntComparator(priorityA, priorityB) // "-" descending order
+func byPriority(a, b Element) int {
+	return -cmp.Compare(a.priority, b.priority) // "-" descending order
 }
 
 // PriorityQueueExample to demonstrate basic usage of BinaryHeap