upgrade extra/libpng to atleast 1.2.35
Security upgrade
[ 1 ] CVE-2008-5907
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-5907
[ 2 ] CVE-2008-6218
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-6218
[ 3 ] CVE-2009-0040
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-0040
(from redmine: issue id 6, created on 2009-03-16, closed on 2009-03-16)