Deprecated lazy vals lose scaladoc under Scala > 2.12

[jrudolph]

From d898589:

The reason seems to be that starting from Scala 2.12 positions are reported
in a way that puts the original position on the private $lzycompute method
instead of on the accessor. To fix that additional considerations are necessary
to somehow reconcile position information from the lzycompute with the actual
accessor so that existing and generated scaladoc can be merged.

Not sure if it makes sense to even fix this on the existing code base. I agree with @jroper in (old) #66 that this tool should probably be rewritten in terms of scaladoc to get rid of all the hacks and to support better translation of formatting details.