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
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
Port Feed, Filesystem, Filter, and Form package unit tests from Platform
Sync Github package to Platform 13.1
Port Google and Grid package unit tests from Platform
Port Image, Keychain, and Language package unit tests from Platform
Modify JHtmlTest::testTooltip to not delete the file
Port Mail, Mediawiki, Model, and Object package unit tests from Platform
Port Plugin, Profiler, Registry, String, and Twitter package unit tests from Platform
Port User, Utilities, and View package unit tests from Platform