#5

[Tejassveer08]

Fixes #5
This PR ports and introduces multithreaded scanning functionality for Python 3.8 in branch feature/python3.8.

Changes:

• Added src/single/scanner.py: single-threaded scanner (py3 reference and fallback).
• Added src/multi/scanner_thread.py: thread-worker utilities with ThreadPoolExecutor.
• Added src/mainScanner.py: user-facing multithreaded port scan CLI supporting port ranges, concurrency and timeouts.
• Added src/ipscanner/ipscanner.py and init.py: utilities for expanding CIDR ranges and multithreaded host probing.

Why:

• Multithreading accelerates port scanning and host discovery for large ranges or many ports.
• The code uses Python 3.8 constructs (concurrent.futures ThreadPoolExecutor).
• Uses TCP-probe approach for host liveness to avoid raw socket / privileged ICMP dependencies.

Notes:

• Behavior mirrors the python2 master implementation (multithreading present there).
• The multithreading design favors ThreadPoolExecutor for simplicity, portability and maintainability in Python 3.
• Logging, argument validation and additional features can be added in subsequent PRs.

How to test:

1. Checkout this branch and run:
   python3 src/mainScanner.py 127.0.0.1 --ports 22,80,443 --workers 50
2. Or test IP scanning:
   python3 -c "from src.ipscanner.ipscanner import expand_cidr, scan_hosts_parallel; print(scan_hosts_parallel(expand_cidr('192.168.1.0/30'), max_workers=50))"

Please review coding style and propose any improvements.