Randomize planet orientation and spin rate

Also adds axis graphic to planet ui representation and slightly
refactors planet js gfx to use shared entity gfx base
UI: tweak a few ship particle effects to better use updated SPE
Remove 'on_target' and 'adjusting_bearing' from follow MS

These attributes can be inferred from other location / movement
strategy properties so do not need to be passed around.

Cleans up related server-side and client-side logic to simplify
things / take care of a few edge cases.

specs / tests need to be written / updated
TODO / Comment Updates, tweak trail particle effect

No major functional changes
UI: few more meshes / textures for different station types