[Open Assets] SRB2 Chars v2

That's right, I've went ahead and added two more characters to this mod, making it a three character pack of Sonic, Tails, and Metal Sonic.
The two newcomers both have all their moves from Sonic Robo Blast 2, and have the capability to break the game even more than Sonic ever did.

Other changes:
- SRB2-style knockback when hit by obstacles and items that'd normally spin you out.
- You'll now drop whatever item you're carrying upon taking damage.
- The Thunder Shield's double jump height has been reduced, as it was accidentally made too high before.
- Proper compatibility with shield monitors.
- Proper compatibility with invincibility, speed shoes, and 1up monitors. (Technically from v1.5, but it wasn't mentioned in that update.)
- Spring panels cause normal Kart gravity.
- SPBs now properly chase you.
- The tire screech sfx will no longer play.
- Attempted to fix mid-race desynchs.
- Custom 3 can now be used to swing the camera behind your character and strafe in the Simple control style.
- Other minor bug fixes.

I realized that SRB2 Sonic actually had a ton of issues with the way his movement was handled, like constantly getting stuck running in one direction, so this update fixes that.
It also makes his gravity and jump height alot more accurate than before, which means jumps are easier to land.
Also changed his pref color to blueberry as blue was definitely too bright for this.
The Simple control style (which is the default) now automatically turns the camera slightly as you move left and right so as to make it not as necessary to baby-sit the camera.
But if you still think you need to baby-sit the camera too much, the Classic control style has been implemented to make sideways movement not move you sideways and instead just turn the camera, eliminating the need for the Custom 1 and Custom 2 buttons all together.
SRB2 Sonic also no longer can perform tricks via Acrobatics, as I felt they were too intrusive to his gameplay style, especially in terms of button management.
Multiple bug fixes have been made as well for a smoother experience.