use quaternions to set orientation of objects in renderer
Allow update_generic_object not to update the orientation by passing NULL orientation quat
allow getting entity orientation quat
add random_quat function
add random_axis_quat function
change sparks to use quaternion for orientation
declare camera_set_orientation in header file
fix some warnings
fix econ ship update

It was relying on heading which is no longer cool.
extract stupid heading from orientation quaternion

(just for now, need to nuke this shit properly at some point)
use quaternion for asteroid spinning
update space station orientation with quaternions
make add_generic_object update entity orientation
fix planet orientation
make derelicts spin randomly via quaternions
make wormholes spin by quaternion
do not try to interpolate heading of player ship

In its current form, it breaks badly when player ship is upside down