[AD] Addons

[Peter H. <pet...@gm...>]

I'm just working my way through the changes resulting from the great
A4 purge (!) I have a question on addons - a lot of the examples now
need the iio and font addons to do very simple things. In my mind,
some parts of those addons should be in the core - for example the
code to register and select an image loader should be in the core,
leaving the implementations (equivalents of jpgalleg and alpng etc) to
go in the addon.

Pete