Allow explicit bundling in the JS/CSS minifier

[tboutell]

Right now the minifier bundles together all the CSS files (or JS files) on the page as a single download. This is a win for that one page, but if you are moving around a site from a page that uses scripts A, B, C and a page that uses scripts B, C and D, you are redundantly downloading the B and C code.

This isn't too bad because in most cases there will be a few distinct combinations like this out there and pretty soon you've cached them all. However, we can do better:

all:

a:

minify:

bundles:

core:

foo.js
bar.js
baz.js

With this option enabled, aMinify should deliver these three scripts as a single bundle if even one of them is requested on a page.

Thanks to Johannes.