cal v1.0.0 - C++ Expression Evaluator

This release introduces cal, a C++ expression evaluator built using a recursive descent parser and a stack-based interpreter.

Key features:

1. Recursive Descent Parsing: Efficiently parses arithmetic expressions with support for basic operations like addition, subtraction, multiplication, and division.
2. Stack Machine Interpretation: Evaluates parsed expressions using a stack-based approach for accurate and efficient computation.
3. Extensible Architecture: The modular design allows for easy extension with additional operators or functionality in future releases.

This version is stable and ready for use in projects requiring lightweight expression evaluation. Feedback and contributions are welcome!