This removes the need to edit the copyright year before generating
the documentation (every year, in several files) and adds some
technical information (doxygen generation date, doxygen version,
and FLTK Git revision) in both HTML and PDF docs.
- auto-generate copyright year (current year) used in several places
- include FLTK Git revision in HTML and PDF docs
- include generation date and doxygen version
- replace special html footer which didn't work well with default footer
The LaTeX header file used when creating PDF documentation depends on
the doxygen and latex versions, respectively.
The old header file 'documentation/src/fltk-book.tex.in' had been
generated manually and needed to be updated for new doxygen versions
which made the PDF documentation generation dependent on the
doxygen/latex versions on the build system.
The new LaTeX header file 'fltk-book.tex' is generated by doxygen,
i.e. taking into account the doxygen and latex versions on the build
system and "edited" to include the page title defined in the new
file 'documentation/src/fltk-title.tex.in'.
This makes the PDF documentation independent of the doxygen and
latex versions of the build system.
