Some refactoring

Small shortenings here and there
here would it be better to just say
```racket
(define-syntax-rule (define-syntax/parse id option-or-clause ...)
  (define-syntax id
    (syntax-parser
      opition-or-clause ...)))
```
so that options like `#:literals` can be used?
So that for example it could be used here: https://github.com/stchang/generic-bind/pull/14/files#diff-3252674930bbd0c4e113856a2a3a5747R293
Also it would probably be better to use define-simple-macro instead of define-syntax-rule, to check that id is an identifier.