Enable scaladoc and "classical" comments

It turns out that `/**` comments fail with the `-Xlint` option, so I just removed it for the `doc` task.
Also there is a weird literal inference with Scaladoc and the `Date` macro. My fix doesn't seem to affect the production code, just the Scaladoc production.
Not sure if this will do the right thing, as in it isn't really tied to any code. Not sure if it makes a difference though.