* doc/website/mainpage.txt: New file representing the input for
the website.
* doc/website/libabigail-website.doxy: New file representing the
doxygen configuration for the website generation.
* doc/api/libabigail.doxy: Output doxygen generation warnings into
a file.
* doc/Makefile.am: Support generating the website from doxygen.
Update the api generation relevant macros names for better
consistency. Make "make html" generate the website too. Make
"make clean" erase the website bits too. Add a 'website'
target to make the website.
Signed-off-by: Dodji Seketeli <dodji@redhat.com>