Replace _tsignal_stopping.wait() with wait_for_stop()

- Introduced new wait_for_stop() method in WorkerClass for better encapsulation
- Updated all direct calls to _tsignal_stopping.wait() to use wait_for_stop()
- Updated documentation to reflect the new method
- Added code formatting improvements and whitespace cleanup
- Bump version to 0.4.4

Merge pull request #7 from TSignalDev/doc

update examples.md