Ok, I got it.

I've just finished the data package subsystem. There's an abstract base class that defines the interface and defines a few basic tasks. Then you can extend it to use any package you want. Right now I've included a simple custom IFF-based package system, format description has been included in documentation.

I had to add a binding between Object Pascal TStream and Allegro's file system too. I had a few problems with this (the way C and Pascal use pointers and parameters makes binding stuff a bit tricky) but now it works seamlessly and you can use Allegro's functions to load stuff (bitmaps, fonts, sounds...) from my package subsystem.

I think it's time to release a new alpha version of the engine. May be this week-end or sooner.