doxygen -u
make Doxygen generation dynamic
add generated Doxygen file to .gitignore
Merge pull request #323 from carstene1ns/doxygen

add Doxygen generation to autotools and make the Doxygenfile dynamic
include autoconf macro explicitely
Merge pull request #324 from carstene1ns/doxygen_autotools_fix

include autoconf macro explicitely