Improvements on instant readings

[catteneo]

Managed to make this work on a Proform 995i
So for starters, thanks for awesome work!

Things I noticed:

• my tradmill bluetooth code has a capitalized letter, if I put it like that software doesn't find the treadmill, so it would better to convert it to lower case to avoid this try/fail.

• the main one for this feature request - some kind of rolling average that can attenuate the instant variations of speed.
  E.g. while trying to run at 11kph the reported speed on average was 10.7/10.8 I guess, but the variations were many and much frequent. And went like 10.5 to 11.5.. several times per second I would say.
  So some kind of rolling average of the last second / 2 seconds could smooth things a lot here.
  Would this be possible?