Updating graphics with new sprites.

[mmcleod89]

• Added the sprites we have into each of the games
• Unified the buttons under a standard button prefab so that any changes made to the menu style update automatically
• Temporarily changed button colours for clarity against the background
• Added scrolling background and flickering flame behind the rocket for Star Collector
• Updated particle effect to use sprites
• Different cursors have been (temporarily) selected for eye, head rotation, and head position. Whatever icons we use should be consistent throughout all games.
• Some file reorganisation since we have an increasing number of prefabs.

Rocket Launch doesn't have a background yet, nor do we have any UI elements yet beyond the cursors.

[mmcleod89]

I had to merge some conflicts between Unity scene files so when reviewing it'd be great if you could help check that nothing's gone missing or changed in an unexpected way. It won't affect any of the code but it might affect which game objects are in the scene or where exactly they are located, but they seem to be playing correctly to me.

[K-Meech]

Thanks @mmcleod89 - the graphics look great!
Unfortunately, I think there are still some issues from the merge conflicts to be resolved e.g.:

• Opening the SpaceWalking and StarMap scenes prints multiple errors to the console
• I can't build the game (File > Build an Run) - it fails with an error message. I can play the games in the unity editor though - so should be fine for the demo.
• The main menu button has disappeared from the win screen (+ the win screen didn't seem to appear upon winning space walking)

There are probably more issues, but only had time to give it a quick play.

[mmcleod89]

Closing because unity scene conflicts are easier to resolve in a new PR!