v1.6.0 to optimize code, etc.

### Releases v1.6.0

1. Add example [ISR_16_Timers_Array_OneShot](examples/ISR_16_Timers_Array_OneShot) to demo how to use `one-shot ISR-based timer`
2. Add example [multiFileProject](examples/multiFileProject) to demo for multiple-file project
3. Optimize code by using passing by `reference` instead of by `value`

Author: khoih-prog