improved the timing and made it configurable

[mamuesp]

Finally found the time to rebase the commits and renew th PR.

What had be done:

• the bitbanging default timing adjusted a little bit
• made the timing settings configurable

[mamuesp]

@rojer - Found an error: in the file mgos_neopixel.h misses the last parameter of

                                           enum mgos_neopixel_order order, int num_channels);```
I may fix it tomorrow or you add the parameter on the fly.

[mamuesp]

@rojer - I have to do it by myself, my header file got mixed up. I close the PR and will open a new one. Sorry!