bibclean 2.16 (new formula)

Build failed with superenv, hence included `env :std`.
`ENV.deparallelize` was also necessary.
Two `inreplace` statements insert `mkdir` statements needed on MacOS.
One `inreplace` statement fixes the `mandir` variable in `Makefile`,
which is not properly defined by autoconfig despite the `--mandir`
parameter passed to `./configure`.
Remove superfluous .
Add comment to inline patches.
Move non-executable files out of bin folder; add caveat.
Refine code comments for clarity.
bibclean: add 2.16 bottle.