Adds automagically generating libvncserver/libvncclient API
documentation using doxygen. This gives a nice overview on both APIs,
include dependencies and function call/caller dependencies.
TODO: Modify all the explaining comments in the .c files for use with
doxygen as well.
This patch only changes comments, no functional changes at all!
Signed-off-by: Christian Beier <firstname.lastname@example.org>