Author: Damyon Wiese
MDL-42671 EditPDF: Disable EditPDF is zlib is not available
Also put a warning on the admin page if this is the case.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=237f4841886802105fcbf00b5c8fe05f4a1c626f
http://github.com/moodle/moodle/commit/237f4841886802105fcbf00b5c8fe05f4a1c626f
+ 2.6 en [zlibenabled,assignfeedback_editpdf]
+ 2.6 en [zlibnotavailable,assignfeedback_editpdf]