better camera, unlock notifications, and other minor changes

i've done a lot of work on the game since the last update but i don't remember everything i've changed. here are some of the bigger things:

• the game now tells you after completing a level what you've unlocked by doing that. hopefully this'll help people know what options they have rather than just going through everything in order.
• the camera has a little bit of damping now! it's nowhere near final but i think it's a decent improvement at least.
• i switched the whole game over from godot's terrible physics engine to box2d ! seems like it's made an improvement but it's hard to tell. sorry if this makes anything impossible as a side effect
• a few of the secrets might be easier to find

nothing huge yet, but i have a few things planned for the (near?) future:

• bonus levels after beating the main set which unlock with gold times -- i'm planning on using these to show some funny gimmicks etc. similar to the latter half of spinny game 1's level set. i've made 2 so far but i have a lot of ideas
• levels that unlock for finding secrets -- i already have 2 (or 4, depending on how you count) but i would like to have one for every secret that isn't ridiculously hard to find
• a better tutorial that gives players space to play around and get a feel for how the spinny guy controls. i'm getting a lot of feedback that the game as it stands doesn't really teach people that effectively
  • i also might make some more open-ended areas even outside of a tutorial, after making the tutorial it seems like there's a lot of potential there

i might release the tutorial on its own pretty soon, but i'm planning on waiting on releasing the bonus & secret levels until there are a few more.  stay tuned, i guess?