Simple mathematical expression parser and evaluator.
Features:
- Variables: t, ...
- Constants: e, pi, ...
- Functions: sin, log, sqrt, ...
- Absolute value: |expr| => abs(expr)
- Respects operator precedence: 1 + 2 * 3 => (1 + (2 * 3))
- Implicit multiplication: 3x => 3 * x
