add libs that are more and more often required by projects
version up : libpng 1.6.6.
version up : X11R7.7.
pypdf2 should now install correctly
remove pypdf as pypdf2 is now working
revert libXrender version because building cairo-1.10.2 failed.
Merge branch 'erp5-component' into erp5
Merge branch 'erp5'