Nuke Op Tweaks

In response to feedback:
Dark Gygax no longer has the scattershot. Instead, it has a modestly powerful carbine loaded with incendiary rounds, solidifying its role as a hit-and-run and squad-support platform.
The Mauler now has the scattershot in addition to its existing arsenal, to give it that edge against crowds that you'll need at those higher populations.

Included with the new mecha weapon is a minor code refactoring of mech guns... There shouldn't be any noticable changes to the user. mech code is awful, guys
New sound effect for mecha launchers (Having the same sound effect for projectile launching and exploding drove me nuts.).

Nuke op flamethrowers now start with a full tank.