Turning off god mode for shields.  Was fun while it lasted.
Added isKinematic to boss1 spawns and turrets to root them to their joints.
Overwhelmed behavior doesn't affect kinematics
Ammo no longer bounces off hero.  A load of other small tweaks.
Fixed tanks.  Some tweaks to improve the timing of alpha changes when fading sprites with child sprites;  a better fix must come later.