Improve support for classes in PetraAI.
Let PetraAI use MatchesClassList more.
Differential revision: https://code.wildfiregames.com/D2150
Reviewed by: Angen
Comments by: Stan
Either causes or exposes https://wildfiregames.com/forum/topic/45178-a25-svn-version-25810-not-playable/.
I guess a concern would be in place.
Should be +.
D4184, but there is more, since she keeps constructing siege without using it.