[Feature Request] Add the Ultimate Artifacts on the map

Right now, there is no way to put Ultimate Artifacts directly on a map. Also, they are random when you place the digging spot on the map. The only other way to put them in a map is to give them to a hero, either by the editor or through scripting.

So is it possible to:
1) Add Ultimate Artifacts to the list of artifacts you can directly place on the map
2) Set which Ultimate Artifact is given by digging

Personnaly, I would prefer a callback as OnHeroDigging(hero, x, y) when a hero digs on the adventure map, this would open up a lot more possibilities for the reward.

We actually are going to be touching this, as one of the scenarios in the main campaign calls for some custom work with digging up an artifact.

I've actually never looked into how the ultimate artifact works. We're probably more likely to implement this feature via scripting than via the map editor as in HoMM III, as in general scripting changes are easier to do.