Manage PCNT_UNIT and PCNT_CHANNEL parameters

[FrankBolleri]

Dear Nikos,
thanks for this fantastic library, it is very useful, precise and elegant.

Maybe was my ignorance, but seems to me that only way to change PCNT_UNIT or PCNT_CHANNEL is to create a "copy" of your code in Arduino IDE Tabs and change the #define values.
If I am wrong, can you tell me how to do it in the right way?
Otherwise, I can suggest you to make these values parametric?

It can be useful if we need to use your library with some other PCNT library, like (in my case) the library ESP32Encoder.
Thanks for attention and for your great work.
Francesco