Author: Petr Škoda
MDL-44824 add missing subplugin type names
http://git.moodle.org/gw?p=moodle.git;a=commit;h=e21117fdc02b29adfea948e9ea4a98406e7a07ad
http://github.com/moodle/moodle/commit/e21117fdc02b29adfea948e9ea4a98406e7a07ad
+ 2.6 en [subplugintype_ltisource,mod_lti]
+ 2.6 en [subplugintype_ltisource_plural,mod_lti]