Unify types for quotient, remainder and quotient/remainder

[capfredf]

use the same spec to generate types for them.

closes #1039

[samth]

We talked and planned to try more random testing on this.

[capfredf]

@samth I have made changes to tr-randoming-testings.rkt. I increased the number of the first two tests to 2000 to make sure the generated expressions does include quotient, remainder, quotient/remainder

[wargrey]

Hello, @capfredf @samth. this PR seems to forget the case of (-> Index Byte Byte).

In original code, there are also no cases of (-> Nonnegative-Fixnum Byte Byte) and (-> Natural Byte Byte), but typed racket seems smart enough to deal with them when the second argument is of Byte.