commit_message.txt

Add Execute option to Code function for conditional code execution

Enhanced Code function with new Execute option:

- Added Execute->True as default option to Code function in Sources/Code.m  
- Modified Code function logic to conditionally execute InputCode based on Execute option
- Added Execute usage declaration in main xPlain.m package file
- Maintains backward compatibility with Execute->True as default behavior
- Allows users to display code without executing it when Execute->False

This provides more flexible control over code display and execution in xPlain documents, useful for showing example code or demonstrations without actually running the computations.