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: https://develop.svn.wordpress.org/trunk@21644 602fd350-edb4-49c9-b593-d223f7449a82
Andrew Nacin