v1.3.0 to fix multiple-definitions linker error

### Releases v1.3.0

1. Fix `multiple-definitions` linker error. Drop `src_cpp` and `src_h` directories
2. Add example [multiFileProject](examples/multiFileProject) to demo for multiple-file project.
3. Optimize library code by using `reference-passing` instead of `value-passing`
4. Update all examples

Author: khoih-prog

README.md

@@ -147,7 +147,7 @@ The catch is **your function is now part of an ISR (Interrupt Service Routine),
    - [`EthernetENC library v2.0.2+`](https://github.com/jandrassy/EthernetENC) for ENC28J60. [![GitHub release](https://img.shields.io/github/release/jandrassy/EthernetENC.svg)](https://github.com/jandrassy/EthernetENC/releases/latest). **New and Better**
    - [`UIPEthernet library v2.0.11+`](https://github.com/UIPEthernet/UIPEthernet) for ENC28J60. [![GitHub release](https://img.shields.io/github/release/UIPEthernet/UIPEthernet.svg)](https://github.com/UIPEthernet/UIPEthernet/releases/latest)
  5. To use with certain example
-   - [`SimpleTimer library`](https://github.com/jfturcot/SimpleTimer) for [ISR_Timers_Array_Simple](examples/ISR_Timers_Array_Simple) and [ISR_16_Timers_Array_Complex](examples/ISR_16_Timers_Array_Complex) examples.
+   - [`SimpleTimer library`](https://github.com/jfturcot/SimpleTimer) for [ISR_16_Timers_Array](examples/ISR_16_Timers_Array) and [ISR_16_Timers_Array_Complex](examples/ISR_16_Timers_Array_Complex) examples.
 
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