NoSpawnAlt and Turret

To store the spawn-less voxel, spawner units with NoSpawnAlt=yes used the same storage space normally used for turrets. Thus, spawner units which should have a spawn-less voxel cannot also have a turret at the same time.

Ares reworked this feature and makes it possible to combine turrets and spawn-less voxels.

New in version 3.0.