v1.2.1 to fix `DutyCycle` and `New Period` display bugs

Releases v1.2.1

1. Fix DutyCycle bug. Check float precisison of DutyCycle only sometimes working #3
2. Fix New Period display bug. Check random dropouts #4
3. Update examples

v1.2.0 to Fix `multiple-definitions` linker error, improve accuracy, DutyCycle to be optionally updated at the end current PWM period instead of immediately, etc.

Releases v1.2.0

1. Fix multiple-definitions linker error. Drop src_cpp and src_h directories
2. Improve accuracy by using float, instead of uint32_t for dutycycle. Check Change Duty Cycle #1
3. DutyCycle to be optionally updated at the end current PWM period instead of immediately. Check DutyCycle to be updated at the end current PWM period #2
4. Optimize library code by using reference-passing instead of value-passing
5. Add example multiFileProject to demo for multiple-file project
6. Update examples accordingly

v1.1.0 to add functions to modify PWM settings on-the-fly

Releases v1.1.0

1. Add functions to modify PWM settings on-the-fly
2. Add example to demo how to modify PWM settings on-the-fly

v1.0.1 to update platform in `library.json`

Releases v1.0.1

1. Fix platform in library.json

v1.0.0 to support ISR-based multi-channel PWM for RP2040-based boards (ADAFRUIT_FEATHER_RP2040, RASPBERRY_PI_PICO etc), using arduinoCore-pico core

Initial Releases v1.0.0

1. Initial coding to support RP2040-based boards such as ADAFRUIT_FEATHER_RP2040, RASPBERRY_PI_PICO, etc. using Earle Philhower's arduino-pico core
2. The hybrid ISR-based PWM channels can generate from very low (much less than 1Hz) to highest PWM frequencies up to 1000Hz with acceptable accuracy.