doc: generate Doxygen's documentation.

* use configure_files to avoid different $ semantics when COMMAND lines
  are expanded in build files. ($$var vs. \$var)
* nmake/gmake no longer needed by cmake, when building doc.
* explicitly copy doc files into build directory to make it clear what
  files each build stage uses.

Documentation can be built with:
   mkdir build/ && cd $_
   cmake -Dbuild_doc=1 ..   # add -G"NMake Makefiles" for nmake
   make docs                # this builds doxygen first

v3: replace file(COPY) with proper generated file tagging.
v2: Remove option to build documentation independently from doxygen.

tested on linux(gmake) and windows(nmake) [thanks albert]

0 files changed, 0 insertions, 0 deletions