Ability to open and close solar array. Added surrounding mars surface.

This release introduces the feature of unfolding- and folding the solar arrays using the A-button on the right controller.

The user can use smooth locomotion (just like in the previous release) with the left thumbstick. The landers' deck is now equipped with a collider, hindering the user from being to locomote inside the lander using smooth locomotion. However, users with enough space can still freely walk inside/crawl under it. The user can currently also locomote inside the solar arrays.

I added a surrounding landscape, ground shadows and an encapsulating hidden boundary hindering the user from moving too far into the landscape.

Release notes 

(Changed) Extend the solar array using the A-button. The two arms and their respective solar arrays fold completely using the same button.

(Added) After being unfolded, the solar array can be folded back in again using the A-button.

(Added) Surrounding landscape.

 (Added) Collider hindering the user from being able to transition inside the lander using smooth locomotion. The user can however freely walk inside the lander manually.