Fix subcells imported from Gen1 maps

[JovialFeline]

This should correct a minor issue with RA/CnC imports of infantry. The subcell number is copied as-is, though ORA's assignment for them is different.

OpenRA/OpenRA.Game/Map/MapGrid.cs

Lines 119 to 124 in 7b82d85

	new(0, 0, 0), // full cell - index 0
	new(-299, -256, 0), // top left - index 1
	new(256, -256, 0), // top right - index 2
	new(0, 0, 0), // center - index 3
	new(-299, 256, 0), // bottom left - index 4
	new(256, 256, 0), // bottom right - index 5

Below, each number is the original subcell index. The SW corner becomes the center and a possible duplicate, while the SE corner replaces the SW one.

 Gen 1      Bleed Import

1     2      1       2
   0            0+3
3     4      4       _

The Gen2 importer has its own adjustments.

OpenRA/OpenRA.Mods.Cnc/UtilityCommands/ImportGen2MapCommand.cs

Lines 286 to 295 in 4fca85f

	var subcell = 0;
	switch (Exts.ParseByteInvariant(entries[5]))
	{
	case 2: subcell = 3; break;
	case 3: subcell = 1; break;
	case 4: subcell = 2; break;
	}
	if (subcell != 0)
	ar.Add(new SubCellInit((SubCell)subcell));

---

I had seen odd subcells on occasion but hadn't dug into it until I noticed Soviets in allies-03 were less likely to be hidden by trees. That is something the enemy does fairly often in Tiberian Dawn as well.

[PunkPun]

LGTM untested

[anvilvapre]

Perhaps use an enum to indicate the direction/index. To avoid similar issues in future.

[JovialFeline]

Perhaps use an enum to indicate the direction/index. To avoid similar issues in future.

Would you prefer that to a comment?

[PunkPun]

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