Updating main repo with GUI updates and shield powerup, organization

* Finishing touches added to the powerup icon gui
* Added a pause menu which can be accessed by ESC
* Organized the Scripts directory into further subdirectories
* Deleted unused Fonts
* Deleting all unneeded assets from 3D Platformer Tutorial
* Getting rid of Assets/Solobot directory and moving everything to Assets
* Minor fix to the pickup/powerup system