automatic WiFi (de)activation via external button

[MightyPork]

(suggestion by M. Wolf)

For times when it might not be great to have the esp AP or client accessible 24/7, have a makefile config that will listen to a GPIO. If it is held up/down for more than x sec (makefile definable), you bring up the wifi.
As an addon for the above... have the wifi go back down if there is no client activity for x sec.