Introduce Save/Load banks for storing different preset settings. (#11)

This also includes a lot of minor fixes.

Reviewed-on: https://git.pinkduck.xyz/adam/libGravity/pulls/11
Co-authored-by: Adam Wonak <adam.wonak@gmail.com>
Co-committed-by: Adam Wonak <adam.wonak@gmail.com>

examples/Gravity/euclidean.h

@@ -66,7 +66,7 @@ class Pattern {
 
     // Update the euclidean rhythm pattern using bitmap
     void updatePattern() {
-        pattern_bitmap_ = 0; // Clear the bitmap
+        pattern_bitmap_ = 0;  // Clear the bitmap
 
         if (steps_ == 0) return;