Fix some problems in the Doxygen-generated man pages (C libraries), the
more noticeable being removing the full path of the files from the
header and synopsis.
Doxygen comments are now used in libowlps, libowlps-client and
libowlps-resultreader. doc/Doxyfile was added as well as CMake rules to
generate man pages for the libraries' header files.
Matteo Cypriani