Re-export each pin type aliases (PA0, PA1, ..) under gpio module

[Piroro-hs]

Pros:

• less typings
• remove redundancy of gpio::gpioa::PA0

Cons:

• Super long "Re-exports" section in rustdoc

[Sh3Rm4n]

Generally in favor of your suggestion.

But what about directly defining these type aliases in the gpio module, instead of the gpio::gpioX module. Does this mitigate the "Re-export" con?

stm32f3xx-hal/src/gpio.rs

Lines 912 to 913 in 2a4382e

	/// Partially erased pin
	pub type $PXx<Mode> = Pin<$Gpiox, Ux, Mode>;

[Piroro-hs]

Super long too but maybe fair enough😃.
However, should we keep gpio::gpioX::PXn for compatibility?

[Sh3Rm4n]

However, should we keep gpio::gpioX::PXn for compatibility?

Hm. 🤔 I don't know? Maybe because this is subtle difference to the other stm32xxxx hal implementations? But maybe not? It is definitely a big change for everyone upgrading a version.

What about a slight conversation phase? Keep them in the old place for one version while introducing the new place and in the version after that remove them?

After I'm finally about to release 0.7 I'll hope to increase the release cadence.