Remove `tunk/Manuals/Texinfo' translation messages. The texinfo
documentation backend is not localized through PO translation
messages.
- Previously, I was taking the XHTML output for producing
translation messages for producing translated versions in XHTML
format. This method is no longer used, so I'm removing all the
translation messages used for it.
- From now on, different texinfo documentation sctructures are
created for each language that we want to support. Since there
is one documentation manual for each language, the output
produced from them is in that language too. Here, we localized
the source files, not the output files.