"==" and "!=" operators.

test/number_equality.wren

@@ -0,0 +1,19 @@
+io.write(123 == 123)  // expect: true
+io.write(123 == 124)  // expect: false
+io.write(-3 == 3)     // expect: false
+
+// Not equal to other types.
+io.write(123 == "123") // expect: false
+io.write(1 == true)    // expect: false
+io.write(0 == false)   // expect: false
+
+io.write(123 != 123)  // expect: false
+io.write(123 != 124)  // expect: true
+io.write(-3 != 3)     // expect: true
+
+// Not equal to other types.
+io.write(123 != "123") // expect: true
+io.write(1 != true)    // expect: true
+io.write(0 != false)   // expect: true
+
+// TODO(bob): Should 0 == -0?