Added Regional School (3x3)

First go around with 3x3 fixed structures...
Added Regional School Spawning

Feel free the change the style/color of the tiles...
Added School Spawn Group
Added School Spawn Group
Added OMS_FLAG_3X3_FIXED

I was playing with pretty rotational matrix when I got fed up and just wrote it out.  Isn't pretty but it works perfectly so far.  The 'if (special.ter == ot_school_2)' adds the road tile in front of the school parking lot that is offset from the entrance.
Merge remote-tracking branch 'dda/pr/864' into dda-master

Conflicts:
	omdata.h