Some [redacted] (yes, myself) had a really bad idea
to rename nest/route.h to nest/rt.h while refactoring
some data structures out of it.

This led to unnecessarily complex problems with
merging updates from v2. Reverting this change
to make my life a bit easier.

At least it needed only one find-sed command:

    find -name '*.[chlY]' -type f -exec sed -i 's#nest/rt.h#nest/route.h#' '{}' +