Beta turrets improved

With some work, turrets now have a fixed rotation arc and properly
target enemies in that range. This uses data from the parent transform,
and if it doesn't have a parent, will default to root.

Additional changes:

Bloom buffer clamped to a maximum of 320*180 for pleasing results.

Lights and associated shader totally ignore worldAngle for now.

Normal defer shader made more compact.

Improved aspect ratio compliance in main window.