Would be handy to have a way to return multiple `Lint`s from a `Linter`/`ExprLinter`

Sometimes, and especially when dealing with grammatical agreement, there are two fixes in different areas, such as a verb form that only works with singular pronouns and nouns mismatched with a plural pronoun or noun.

When there are other words in between, you can only handle that by returning multiple `Suggestion`s on the same `Lint` with the same `span` and therefore the `span` must cover the full extent of text that encompasses both parts that can be fixed.

It would be easier to code, and the code would be easier to read, if you could return two `Lint`s, each with a `span` just for the part it needs to fix.