Add diamond exercise as custom exercise

ErikSchierboom · ErikSchierboom · commit b3260c4470a3 · 2017-12-14T22:24:41.000+01:00
diff --git a/generators/Generators.fs b/generators/Generators.fs
@@ -226,6 +226,9 @@ type CollatzConjecture() =
 type CryptoSquare() =
     inherit GeneratorExercise()
 
+type Diamond() =
+    inherit CustomExercise()
+
 type DifferenceOfSquares() =
     inherit GeneratorExercise()
 
