Author: Petr Škoda
MDL-38121 tell admins when plugin installed into wrong dir
http://git.moodle.org/gw?p=moodle.git;a=commit;h=bdbcb6d7fa0c74d37d6b9d579c57ff1e6e3b26e4
http://github.com/moodle/moodle/commit/bdbcb6d7fa0c74d37d6b9d579c57ff1e6e3b26e4
+ 2.5 en [detectedmisplacedplugin,core_plugin]