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

@@ -17,11 +17,6 @@
   * [Why using ISR-based Hardware Timer Interrupt is better](#why-using-isr-based-hardware-timer-interrupt-is-better)
   * [Currently supported Boards](#currently-supported-boards)
   * [Important Notes about ISR](#important-notes-about-isr)
-* [Changelog](#changelog)
-  * [Releases v1.2.0](#releases-v120)
-  * [Releases v1.1.1](#releases-v111)
-  * [Releases v1.0.1](#releases-v101)
-  * [Releases v1.0.0](#releases-v100)
 * [Prerequisites](#prerequisites)
 * [Installation](#installation)
   * [Use Arduino Library Manager](#use-arduino-library-manager)
@@ -303,6 +298,8 @@ in many files. But be sure to use the following `.h` files **in just 1 `.h`, `.c
 #include "Teensy_ISR_Timer.h"           //https://github.com/khoih-prog/Teensy_TimerInterrupt
 ```
 
+Check the new [**multiFileProject** example](examples/multiFileProject) for a `HOWTO` demo.
+
 
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