Asteroids Blow Up Each Other Now, also houses and skyscrapers

Heya!

Changes:

-Asteroids will blow up when they hit each other as if you had shot them, this should lead to some fun chaos.

-Added some more structures to planets! These arent permanent just an idea of the style i want to go for!

-Comets have a proper LOD

-Fix  dbug that would happen if you spam clicked a button that loads a scene (eg restart or enter the realm) that would result in a game freeze

-Parralelized gravity calculations increasing fps by like 200