Add pointwise natural transformations.

I'm not terribly happy with the name.  I've asked for a better one on
http://mathoverflow.net/questions/141022/naming-ambiguity-in-constructive-pointwise-natural-transformations-and-whiskerin

After    | File Name                             | Before
-----------------------------------------------------------
0m23.60s | Category/Equality                     | 0m23.01s
0m23.48s | Adjoint/Hom                           | 0m23.15s
0m22.62s | Comma/Duals                           | 0m23.38s
0m12.13s | Adjoint/UniversalMorphisms            | 0m12.68s
0m11.79s | Adjoint/Composition                   | 0m12.58s
0m11.54s | Adjoint/Duals                         | 0m11.58s
0m11.00s | Adjoint/UnitCounitCoercions           | 0m10.75s
0m08.26s | Comma/InducedFunctors                 | 0m08.02s
0m07.30s | Groupoid                              | 0m07.35s
0m06.64s | Adjoint/Equality                      | 0m06.68s
0m05.64s | Adjoint/UnitCounit                    | 0m05.21s
0m05.44s | Category/Morphisms                    | 0m05.28s
0m04.78s | SumPreCategory                        | 0m04.97s
0m04.58s | Groupoid/Duals                        | 0m04.30s
0m04.20s | Functor/Equality                      | 0m04.18s
0m03.68s | Groupoid/Functors                     | 0m03.58s
0m03.68s | UniversalProperties                   | 0m03.62s
0m02.82s | Grothendieck/ToSet                    | 0m02.76s
0m02.44s | NaturalTransformation/Pointwise       |   N/A
0m02.39s | Comma/CommaCategory                   | 0m02.52s
0m02.36s | BoolCategory                          | 0m02.49s
0m01.94s | NaturalTransformation/Duals           | 0m01.84s
0m01.92s | Hom                                   | 0m01.81s
0m01.88s | Category/Product                      | 0m01.92s
0m01.80s | NaturalTransformation/Equality        | 0m01.82s
0m01.55s | NaturalTransformation/Product         | 0m01.62s
0m01.37s | NaturalTransformation/Composition     | 0m01.34s
0m01.28s | NaturalTransformation/CompositionLaws | 0m01.20s
0m01.26s | Functor/Product                       | 0m01.22s
0m01.17s | NaturalTransformation/Isomorphisms    | 0m01.10s
0m00.79s | Cat/Morphisms                         | 0m00.80s
0m00.70s | FunctorCategory/Morphisms             | 0m00.61s
0m00.63s | InitialTerminalCategory               | 0m00.60s
0m00.50s | Functor/Pointwise                     | 0m00.48s
0m00.48s | Functor/CompositionLaws               | 0m00.43s
0m00.42s | Comma/Projection                      | 0m00.51s
0m00.38s | IndiscreteCategory                    | 0m00.38s
0m00.33s | Discrete/Duals                        | 0m00.37s
0m00.30s | SetCategory                           | 0m00.32s
0m00.29s | Cat                                   | 0m00.30s
0m00.29s | Common                                | 0m00.32s
0m00.28s | FunctorCategory                       | 0m00.31s
0m00.26s | Category/Objects                      | 0m00.26s
0m00.25s | NaturalTransformation/Identity        | 0m00.30s
0m00.23s | IsGroupoid                            | 0m00.21s
0m00.23s | Functor/Duals                         | 0m00.27s
0m00.22s | NatCategory                           | 0m00.23s
0m00.21s | Functor/Composition                   | 0m00.20s
0m00.20s | ComputableCat                         | 0m00.14s
0m00.19s | Category/Core                         | 0m00.18s
0m00.19s | Adjoint                               | 0m00.16s
0m00.19s | NaturalNumbersObject                  | 0m00.18s
0m00.17s | Adjoint/Identity                      | 0m00.16s
0m00.15s | NaturalTransformation/Core            | 0m00.14s
0m00.14s | NatCategory/Duals                     | 0m00.18s
0m00.14s | Category/Duals                        | 0m00.13s
0m00.14s | Grothendieck                          | 0m00.10s
0m00.13s | Functor/Core                          | 0m00.15s
0m00.13s | Utf8                                  | 0m00.12s
0m00.13s | Peano                                 | 0m00.12s
0m00.12s | DiscreteCategory                      | 0m00.10s
0m00.11s | Category/StrictCategory               | 0m00.06s
0m00.10s | Functor/Identity                      | 0m00.09s
0m00.10s | Category/UnivalentCategory            | 0m00.12s
0m00.09s | Functor                               | 0m00.10s
0m00.08s | Category                              | 0m00.06s
0m00.08s | NaturalTransformation                 | 0m00.11s
0m00.04s | NotationsUtf8                         | 0m00.06s
0m00.04s | Notations                             | 0m00.04s
-----------------------------------------------------------
3m23.99s | Total                                 | 3m21.35s