Improve API to allow having an array of Analog pins

[pum-purum-pum-pum]

It would be great to be able to store analog pins in the array and process them sequentially.
If one needs to have multiple analog pins in the array it's not possible -- types are different and Channel trait has type-associated function.

Currently, Adc implements OneShot trait which accepts pin.

stm32f0xx-hal/src/adc.rs

Line 604 in 9f21c49

impl<WORD, PIN> OneShot<Adc, WORD, PIN> for Adc

The pin argument itself is not used, but the associated function of its type channel (which is the channel id) is used instead.

Perhaps we can change the function to fn channel(&self) but it might break some assumptions. Would be great to hear some input

[newAM]

Perhaps we can change the function to fn channel(&self) but it might break some assumptions.

That is one of the changes coming in the 1.0.0 release of embedded-hal: https://docs.rs/embedded-hal/1.0.0-alpha.7/embedded_hal/adc/nb/trait.Channel.html

Would be great to hear some input

Do you know of other STM32 HALs that have this feature? Maybe there's an elegant way to support the trait from the current stable version and the alpha?