New mechanics

This update adds some new mechanics and elements to the game:

• Moving platforms
• A collectable item that unlocks progress (and a basic inventory UI)
• Backtracking
• A cave that the player can enter

I added these elements, because I felt that I wasn't able to expand the game any further with the existing mechanics (basic platforming and grappling hook). I could've just decided that this is a small game and call it complete (like the initial plan was 🫠), but I still like working on it and I think the art style has potential for a bigger game. Let's see where it goes!

I also added a bloom effect which took me way longer to make than it should have: