Parallel to rP13060 change the attack related sounds so multiple attacks are allowed.
Also adding some missing sounds in templates f.e. siege tower. And impact sound for all archers (instead only infantry) and bolt shooters.
On the way too that re-order the sounds, so they are logically defined in the templates.
Fixing slaughter sounds, since currently a ranged unit makes another sound when attacking a sheep than a melee unit, using the same dagger. Both will use the sword sound after the patch.
The mauryan siege elephant (and some other units) still miss attack sounds, due to missing event tags in the actors. But that falls out of scope for this patch (see https://github.com/bb-bb/0ad/tree/attackSounds for commits fixing that and other related issues and cleanup)