Optimized importPiece, drawPiece, & drawShadow; tweaked spawns

- Implemented relatively simple exceptions to importPiece, drawPiece, and drawShadow based on the piece types being used, replacing the inefficient stopgap methods employed previously.
- The above change made pieces spawn as expected, so that and their spawn locations are now easy to adjust.
- Some unnecessary parameters were removed from various functions, and math.h was removed as it is never used.