Author: Luca Bösch
MDL-59460 mod_forum: default setting for Subscription mode.
Allow to set a Subscription mode default.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=58affdc80e44cec0e139f97fd7d01416648c1199
http://github.com/moodle/moodle/commit/58affdc80e44cec0e139f97fd7d01416648c1199
+ 3.4 en [configsubscriptiontype,mod_forum]