Add assets by type to the node to provide conveniently organized assets to the theme

Often you want to display assets in a organized fashion in the theme, and it is a fair amount of work to load and sort each one. This is a little module that adds an array to the node of all the assets sorted by extension and type.

This could be incorporated into the regular asset nodeapi view op (which, as far as I could tell seems to be broken right now anyway...another day perhaps) - but I am not sure people would always want to clutter up the node object with duplicate copies of assets. The other thing would be to make this an option in asset_content.inc, but that would be quite a bit more work, and needs more thought.