Support AVR expect for atmega256x (Arduino MEGA etc)

[asukiaaa]

I merged the following scheduler project to this project.

https://github.com./fabriceo/SCoop/tree/master/SchedulerARMAVR

Arduino nano and Arduino Leonardo can play multiple blinks with this scheduler but Arduino MEGA cannot.
(I don't test with DUE and ZERO because I don't have them.)

I know that another pull request was created but it seems stop.
#1

This scheduler does not support MEGA but it is useful that we can create multi threading project on NANO, UNO, Leonardo etc with this Scheduler.

Thanks for your consideration.

[facchinm]

Hi @asukiaaa ,
thanks for pointing it out, but enhancing Scheduler is not currently in the TODO list. We'll take care analysing the PR sooner or later. In the meantime you can always propose a scheduler library for AVR for inclusion in the library manager.

[asukiaaa]

Hi @facchinm , thank you for your response.
OK, I wait your analyzing.

[CLAassistant]

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