Custom AltHud class

[Graf Zahl]

No concerns. It still needs some work for easier use but what's there is enough to get people started.

But one piece of warning to a certain type of modder: Should I see a single case of this being abused to render the AltHud useless I'll add an override switch.
The point here is to allow customization of the contents, not to do something completely dfifferent.

[_mental_]

Well, for some horror standalone game making AltHUD empty (or very limited) is a viable option. For Doom mod it's a nonsense indeed. Ability to force internal AltHUD was added just for this case.