Initial value should reflect the startup value (when no delay)

[cesaregiannetti]

The initial_value configured on gpiozero LED class is OFF.
STARTUP value is applied afterwards.
This is an issue when restarting OctoPrint, because the pins are momentarily driven OFF.

I have a power supply controller connected to a GPIO pin that should be ON while OctoPrint is running, but I can't restart the server (for example after upgrading) because the power is cut after restart (it doesn't turn on again, it can only turn off).

I would like the LED to have an initial_value equal to startup value when the delay is 0.

On this matter, I have another suggestion: LED accepts active_high parameter, which can be set to not inverted, so that XORing with inverted can be avoided when reading or writing. I'll try to issue a PR

[cesaregiannetti]

I found a very simple and neat solution: initial_value=None.
I tested it successfully for my use case and I believe this is the intended use of the parameter.
gpiozero documentation states:

If None, the LED will be left in whatever state the pin is found in when configured for output

Moreover, this doesn't need the dirty trick of fetching the STARTUP value (thankfully, because I didn't understand which call to ensure actually instantiate the LED class).

Now #355 becomes relevant, because it conflicts with the change I want to make