the name of `notFollowedBy` is not consistent with the semantics of the other parsers

Just a small thing if you want, i'm pointing this out while approaching Parsec, before getting used to this.

Usually a parser's name refers to the current parser input. `char 'a'` will parse `'a'` and so on.

If we read `notFollowedBy` with the same semantics, a parser like `notFollowedBy '.'` should correctly parse `"."` because `"."` _is not followed by a dot_. It should fail for "a.", instead.

In this sense a parser called `notFollowedBy` should probably get two parsers as arguments, like `manyTill` etcetera. I find that the current semantic of `notFollowedBy` is closer to a simple `not`.