Make Range a native object type.

Still need to implement better semantics, but this is an 
important first step. It's much faster now too, which is good.

test/range/to.wren

@@ -0,0 +1,25 @@
+// Ordered range.
+IO.print((2..5).to) // expect: 5
+IO.print((3..3).to) // expect: 3
+IO.print((0..3).to) // expect: 3
+IO.print((-5..3).to) // expect: 3
+IO.print((-5..-2).to) // expect: -2
+
+// Backwards range.
+IO.print((5..2).to) // expect: 2
+IO.print((3..0).to) // expect: 0
+IO.print((3..-5).to) // expect: -5
+IO.print((-2..-5).to) // expect: -5
+
+// Exclusive ordered range.
+IO.print((2...5).to) // expect: 4
+IO.print((3...3).to) // expect: 2
+IO.print((0...3).to) // expect: 2
+IO.print((-5...3).to) // expect: 2
+IO.print((-5...-2).to) // expect: -3
+
+// Exclusive backwards range.
+IO.print((5...2).to) // expect: 1
+IO.print((3...0).to) // expect: -1
+IO.print((3...-5).to) // expect: -6
+IO.print((-2...-5).to) // expect: -6