Improve `@see` output

There are some invalid uses of `@see` in JDK API docs, apparently to work around the shortcomings of the current output.

The current output is simply a comma-space separated list of `@see` items.

It would be better if the list used `<ul>` if there are long items or items containing whitespace or commas. Put the other way, use `<ul>` by default, unless all the items are simple words, e.g. like type-names.