[ZH] Make USA Particle Cannon Laser reselectable

[Caball009]

• Implements feature USA Particle Cannon Laser cannot be selected #966

Reselecting the USA Particle Cannon Laser can only be done from the structure it originates from, which is mildly inconvenient.
Draft for now; would need to be replicated in Generals.

I got it mostly working but ran into some issues. In the end I just assigned the objectID of the 'parent' Particle Cannon structure as producerID to the drawable that gets created upon firing the PC. I also modified the mouse selection code to make the laser beam selectable and added a lookup for the producerID to select the 'parent' PC structure. These are the current issues:

1. The laser cannot be selected by clicking anywhere, it has to be done by dragging a selection region.
2. The drawable that gets created, "SuperweaponPing", is fixed in place. So the laser beam is only selectable at the initial coordinates.
3. Anything that's selectable in the region around the initial coordinates may hinder the selection process. The lifetime of the ping outlasts the laser beam by a couple of seconds, so this might make it harder to select the right PC when firing multiple PCs at a specific location.

There's probably a better way to do all this, though.