Merge pull request #5757 from pchote/tsshroud

Use TS shroud sprites.
Remove redundant FindActorsInBox helpers.
Add World parameter to Target.FromOrder.
Add World parameter to Target.FromCell.
Add World parameter to Util.BetweenCells.
Replace CPos.CenterPosition -> Map.CenterOfCell.
Remove WVec.ToCVec.
Replace WPos.ToCPos -> Map.CellContaining.
Remove conversions between legacy and world types.
Remove CVec -> WVec conversion.