The following changes should make the manual more available, and easier
to understand:
1) "make dist" and "make install" will now include all translations of
the manual.
1) A "freedoom-" prefix will be used in all cases in place of just
"manual".
2) All languages will have a two letter suffix, so English is now
"-en".
3) Only the PDF specified will be built when invoked in the top level
directory. For example:
make manual/freedoom-manual-en.pdf
