Leverage embedded-time

[Sh3Rm4n]

We have some extension traits, which define times and frequencies in src/time.rs.

This module is mostly a 1:1 copy, which can be found in almost every stm32f*-hal.
It mostly used internally, but gets also exposed, to configured clocks and timers.

Wouldn't it be nicer to use embedded-time to replace the current time module?

Maybe we can leverage some more features of this crate.

[wbuck]

So I forked the project, removed the custom time module and replaced it with embedded-time. It was almost a drop-in replacement. I altered the serial constructor to take a Baud type instead of the original Bps.

I only built it for the stm32f303xc but it did build with no issues.
I'm fairly new to Rust so I'm unsure what the expectation is regarding re-exporting a third party crate.
So to minimize changes I added the following to lib.rs

pub use embedded_time as time;

[David-OConnor]

Please make a PR.

[strom-und-spiele]

@Sh3Rm4n thanks for proposing this. And thanks to @wbuck for giving a nice example on how to "leverage some more features of this crate" in #191.
Reading about its fixed-point arithmetic under the hood made me like this purpose even more 👍

[Sh3Rm4n]

Closed by #192