Uses individual files for each class. We now conditionally load only the pieces
we need, resulting in less memory usage. Also easier to maintain now that it is
not a single 387KB file.
fixes#21183.
git-svn-id: http://core.svn.wordpress.org/trunk@21644 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Andrew Nacin