Added ability to add sprintf variables to JText string

[writing it up now...]
Merge remote-tracking branch 'remotes/upstream/master' into patch-9
Merge remote-tracking branch 'remotes/upstream/master' into patch-9
Merge remote-tracking branch 'remotes/upstream/master' into patch-9
Added ability to use custom non-language string as first part (can be used for concatenating other strings)
Merge remote-tracking branch 'remotes/upstream/master' into patch-9
Merge remote-tracking branch 'remotes/upstream/master' into patch-9
Merge remote-tracking branch 'remotes/upstream/master' into patch-9
Merge remote-tracking branch 'remotes/upstream/master' into patch-9
 # [#30774] *SEF plugin issue. Thanks Robert Segura.
(Fix #1077)
 #$ [#30737] Incorrect title of the User Note Categories Manager
Fix system tests for clearfix class in front end
Merge remote-tracking branch 'remotes/upstream/master' into patch-9
Fix up doc blocks as example for Webdriver page classes and tests.
Added test for Tag Manager. Thanks Puneet Kala.
# [#30694] Backend toolbar buttons have forbidden attribute href. Thanks
David Hurley
 #$ [#30805] *Isis: sidebar background colour issue
 # [#30103] Cannot delete web site entry for a contact. Thanks Elin
Waring
(fix #1085)
 # [#30748] *Multilanguage issue with contacts. Thanks Benjamin Trenkle
 #$ [#30788] com_newsfeeds title is inconsequent in the backend.