jQuery is a JavaScript library designed to simplify the client-side
scripting of HTML.
I'm adding version 1.x instead of 2.x because 1.x supports IE 6, 7, 8
browsers and both versions are API compatible.
http://jquery.com/
The current version (v1.10.4) is now called "legacy". The new stable version
has a different directory layout; it no longer splits css/ and js/ directories.
Since the *.js files refer to the *.css files by relative paths, I'm not
splitting them. Everything now goes to "$out/js/".
Also, upstream removed version numbers from filenames, so we don't need to
create those version-less symlinks anymore.