Add busty Twig filter/function for cache busting URLs

[jedso]

Usage example:

<script src="{{ 'SKIN/assets/js/example.js'|busty }}"></script>

or

<script src="{{ busty('SKIN/assets/js/example.js') }}"></script>

There is also an optional sub_directory argument for extra flexibility. For example, if Kohana::config('core.site_domain') is set to "/", but the skin/ directory lives within a sub-directory such as app/, then you can provide this:

<script src="{{ 'SKIN/assets/js/example.js'|busty('app/') }}"></script>

or

<script src="{{ busty('SKIN/assets/js/example.js', 'app/') }}"></script>

The end result is a URL with a query string parameter of _v and the file's timestamp. The logic assumes that the URL provided does not already have query string parameters.

[gwillz]

I was following and nodding along until the sub_directory part. I assume this is because an the alternate docroot config?

We don't need to splatter that base config all through the templates, ew. Instead of BASE_PATH use DOCROOT.

I can see that's not obvious because we've not documented those base constants very well and they changed a fair bit after sprout 3.2.

[gwillz]

Send it.