Move CommaCategory
Make IsStrictCategory and IsCategory notations

This makes typeclass resolution a bit better, I hope, though we have to
add [cbv beta] and [assumption] hints.

After    | File Name                             | Before
-----------------------------------------------------------
0m27.25s | Category/Equality                     | 0m25.03s
0m17.94s | Functor/Equality                      | 0m16.66s
0m15.26s | NaturalTransformation/Equality        | 0m15.25s
0m11.42s | Comma/CommaCategory                   | 0m11.41s
0m07.66s | Category/Morphisms                    | 0m07.28s
0m05.18s | Groupoid                              | 0m05.05s
0m04.47s | Grothendieck/ToSet                    | 0m04.98s
0m02.23s | NaturalTransformation/Composition     | 0m02.20s
0m02.22s | Functor/CompositionLaws               | 0m02.16s
0m02.04s | SumPreCategory                        | 0m01.88s
0m01.89s | ProductPreCategory                    | 0m01.87s
0m01.40s | NaturalTransformation/CompositionLaws | 0m01.38s
0m01.32s | NatCategory                           | 0m01.24s
0m01.12s | InitialTerminalCategory               | 0m01.10s
0m00.72s | BoolCategory                          | 0m00.85s
0m00.52s | SetCategory                           | 0m00.49s
0m00.34s | Common                                | 0m00.31s
0m00.25s | NaturalTransformation/Identity        | 0m00.27s
0m00.24s | FunctorPreCategory                    | 0m00.24s
0m00.24s | Functor/Composition                   | 0m00.23s
0m00.16s | Category/Core                         | 0m00.17s
0m00.12s | NaturalTransformation                 | 0m00.08s
0m00.12s | ComputableCat                         | 0m00.16s
0m00.12s | Peano                                 | 0m00.11s
0m00.10s | Category/StrictCategory               | 0m00.08s
0m00.10s | Functor/Core                          | 0m00.15s
0m00.10s | Category/Category                     | 0m00.10s
0m00.09s | Functor/Identity                      | 0m00.09s
0m00.09s | Utf8                                  | 0m00.09s
0m00.09s | DiscreteCategory                      | 0m00.08s
0m00.09s | NaturalTransformation/Core            | 0m00.12s
0m00.08s | Functor                               | 0m00.09s
0m00.07s | Grothendieck                          | 0m00.11s
0m00.05s | Notations                             | 0m00.04s
0m00.03s | NotationsUtf8                         | 0m00.02s
-----------------------------------------------------------
1m45.12s | Total                                 | 1m41.36s