Upgrade 3D Visuals in Backgrounds

remove earth and sun models
add 8 NASA planet models
create star from isosphere with emissiveness
enable bloom on cameras
and RunEndEvent that is sent when a run is ended
create "star explosion effect" when game is lost due to defense depletion
added 84 DALLE generated space backgrounds
add procedural generation for background scenes (random planet, background, star color, and star position)
add new backgrounds resource for configuring background generation parameters
resolve some warnings for unused variables
remove commented code

thetawavegame / thetawave