An offline manual for 5.1.6 has been generated. [See the list of manual translations and downloads.]
Gary has also added a wiki page about creating these offline manual files. It describes the workflow for using the template Scripts to generate an offline 5.1.x HTML manual and converting that to a nicely cross-referenced PDF.
Separate script templates are included for creating the offline manual in 4 languages. Translators are encouraged to adapt the scripts for building offline manuals in their own language. New translations can be linked to the User Manual Translations page.