Add some useful rewriting lemmas.

Pseudofunctors are slow :-(

After    | File Name                             | Before
-----------------------------------------------------------
1m01.76s | Pseudofunctor/FromFunctor             | 1m06.34s
0m25.12s | Pseudofunctor/Core                    | 0m03.19s
0m23.52s | Category/Equality                     | 0m23.90s
0m22.15s | Adjoint/Hom                           | 0m22.79s
0m21.94s | Comma/Duals                           | 0m21.97s
0m12.19s | Adjoint/Composition                   | 0m12.72s
0m12.18s | Adjoint/Duals                         | 0m10.96s
0m12.10s | Adjoint/UniversalMorphisms            | 0m12.14s
0m10.60s | Adjoint/UnitCounitCoercions           | 0m10.38s
0m08.05s | Comma/InducedFunctors                 | 0m07.87s
0m07.40s | Groupoid                              | 0m07.35s
0m06.28s | Adjoint/Equality                      | 0m06.63s
0m06.06s | Category/Morphisms                    | 0m06.02s
0m05.78s | Adjoint/UnitCounit                    | 0m05.59s
0m04.77s | SumPreCategory                        | 0m04.75s
0m04.40s | Groupoid/Duals                        | 0m04.36s
0m04.06s | Functor/Equality                      | 0m04.10s
0m03.70s | Groupoid/Functors                     | 0m03.72s
0m03.49s | UniversalProperties                   | 0m03.52s
0m02.77s | Grothendieck/ToSet                    | 0m02.65s
0m02.65s | Comma/CommaCategory                   | 0m02.68s
0m02.53s | BoolCategory                          | 0m02.45s
0m02.35s | NaturalTransformation/Pointwise       | 0m02.49s
0m02.02s | Category/Product                      | 0m01.88s
0m01.86s | NaturalTransformation/Duals           | 0m01.95s
0m01.83s | NaturalTransformation/Isomorphisms    | 0m01.84s
0m01.81s | NaturalTransformation/Equality        | 0m01.84s
0m01.80s | Hom                                   | 0m01.74s
0m01.74s | FunctorCategory/Morphisms             | 0m01.72s
0m01.54s | NaturalTransformation/Product         | 0m01.39s
0m01.34s | NaturalTransformation/Composition     | 0m01.25s
0m01.28s | NaturalTransformation/CompositionLaws | 0m01.25s
0m01.28s | Functor/Product                       | 0m01.32s
0m00.64s | InitialTerminalCategory               | 0m00.70s
0m00.46s | Functor/Pointwise                     | 0m00.46s
0m00.43s | Comma/Projection                      | 0m00.41s
0m00.42s | Functor/CompositionLaws               | 0m00.47s
0m00.36s | Common                                | 0m00.32s
0m00.35s | SetCategory                           | 0m00.34s
0m00.34s | IndiscreteCategory                    | 0m00.36s
0m00.32s | Cat                                   | 0m00.32s
0m00.32s | Discrete/Duals                        | 0m00.35s
0m00.30s | FunctorCategory                       | 0m00.31s
0m00.30s | NaturalTransformation/Identity        | 0m00.29s
0m00.27s | Cat/Morphisms                         | 0m00.34s
0m00.26s | Category/Objects                      | 0m00.24s
0m00.25s | Functor/Duals                         | 0m00.27s
0m00.24s | IsGroupoid                            | 0m00.19s
0m00.22s | NatCategory                           | 0m00.20s
0m00.22s | Functor/Composition                   | 0m00.22s
0m00.20s | Category/Core                         | 0m00.18s
0m00.18s | ComputableCat                         | 0m00.19s
0m00.18s | Category/Duals                        | 0m00.16s
0m00.16s | Adjoint                               | 0m00.18s
0m00.16s | Adjoint/Identity                      | 0m00.14s
0m00.15s | Pseudofunctor                         | 0m00.12s
0m00.15s | NatCategory/Duals                     | 0m00.18s
0m00.14s | NaturalNumbersObject                  | 0m00.20s
0m00.14s | Category/UnivalentCategory            | 0m00.12s
0m00.14s | NaturalTransformation/Core            | 0m00.19s
0m00.12s | Functor/Core                          | 0m00.14s
0m00.12s | Grothendieck                          | 0m00.11s
0m00.10s | DiscreteCategory                      | 0m00.11s
0m00.10s | Peano                                 | 0m00.10s
0m00.09s | Functor                               | 0m00.09s
0m00.09s | Utf8                                  | 0m00.08s
0m00.08s | Category                              | 0m00.08s
0m00.08s | NaturalTransformation                 | 0m00.11s
0m00.08s | Category/StrictCategory               | 0m00.10s
0m00.07s | Functor/Identity                      | 0m00.06s
0m00.06s | NotationsUtf8                         | 0m00.04s
0m00.04s | Notations                             | 0m00.06s
-----------------------------------------------------------
4m50.67s | Total                                 | 4m33.27s