Added virtual functions to allow easy adaption to other button-types … (e.g touch or IO extender)

[euphi]

To be able to use Atm_button for buttons that are not directly connected to a GPIO I created virtual methods

	  virtual void initButton();
	  virtual bool isPressed();
	  virtual bool isReleased();

initButton() is called from begin() to initialize the button (e.g. set INPUT_PULLUP) the other methods are called from event() to check if they trigger the related event.

The default implementation still has the same behaviour as before, but this allows to derive an own class and overwrite these methods, so you can read other PINs, e.g a touch controller (like MPR121) or IO expander (PCF8575).

See https://github.com/euphi/ESP-Touch/blob/Display_WS2812/src/AtmTouchButton.cpp & https://github.com/euphi/ESP-Touch/blob/Display_WS2812/src/AtmTouchButton.h
for example usage with MPR121 I2C touch controller.

[euphi]

I also added similar functionality to Atm_LED

[euphi]

Examples for Atm_LED:

https://github.com/euphi/RFID_CardReader/blob/master/Software_ESP/src/Atm_led_mcp.h
https://github.com/euphi/RFID_CardReader/blob/master/Software_ESP/src/Atm_led_mcp.cpp