Added QuietDrift support for Curtain 3

[den-mko]

Added speed to open, close and set_position methods. "00" or "ff" - normal, "01" - slow #222

[bdraco]

I adjusted the code a bit to make it easier to follow.

Please retest. I'll merge it and do a release if it works as expected

[den-mko]

Small typing fix. Tested successfully.

[Brephlas]

There is still a pull request needed to upgrade the integration in the HA core similar to this one, right?
@den-mko Do you want to create one? If not, I could do that too

[den-mko]

I already wrote the code with curtains speed changing features but did not have time to submit a PR. Will try to submit it tomorrow

[lightheaded]

It has now been incorporated into HA core. How would one go about using quietdrift now?

[quenthal]

I already wrote the code with curtains speed changing features but did not have time to submit a PR. Will try to submit it tomorrow

Is it already in your fork?

[quizzical86]

@den-mko would you happen to have any news on enabling support for quietdrift?