Previously, the Micro AI behavior was inconsistent at best when it came
to dealing with these units and could even result in AI errors when an
AI unit was ambushed or a petrified unit was in the way of a move. Now,
both types of units are properly "ignored" and the AI moves have been
made robust against unexpected events such as ambushes. Incidentally,
the latter also makes the AI more robust against WML events doing
things the AI cannot know about (such as removing units).
This can either be an [avoid] tag inside the [micro_ai] tag itself, or
the [avoid] tag of the default AI (e.g. as defined in the side
definition). If both are given, the former has priority.
