This patch update doxygen configuration to have all possible functions
documented (even the one without doxygen formated comments). It can be
really useful to have that in case we are trying to get some information
on call graph for example.
This patch sets some define to generate doc for the acquisition
modules. It also suppress the doc generation for unittests which
was polluting the output.
Generated documentation for unittests and other module was not
generated because doxygen was not assuming the define to be set.
This patch adds the necessary define for unittests and does the
same for NFQ, PFRING, IPFW, AF_PACKET and Prelude. This also adds
a variable that permit parallelisation of dot file generation.