Update version number to 2.4.2
Strict null check on group parameter
Sync skel and app directories.

Closes #1698
Add space between classname(s)
Merge pull request #2180 from bcrowe/hotfix-strict

Strict null check on group parameter
Merge pull request #2181 from bcrowe/hotfix-classname

Add space between classname(s)
Renamed $sortby to $sortBy in sortByKey
Fix delivery issues with long subject lines and MailTransport.

A few people have reported issues sending wrapped messages via
MailTransport. Removing the new lines has been suggested as a fix.

Refs #2176
Merge pull request #2184 from ravage84/sortby

Renamed $sortby to $sortBy in sortByKey