new function hooks in KeyboardController class

[kunzjacq]

in KeyboardController class:

• added a new hook, reportReaderFunction, to enable the client code to read raw incoming keybooard state reports (called from method new_data)
• added a new hook, modifiersChangedFunction, to enable the client code to be notified when modifiers state is changed but no key is pressed or released
• initialized all function pointers to zero in both KeyboardController constructors
• changed led state change behavior: leds are updated when keys are pressed, not when they are released, as with most keyboards (methods key_release and key_press)
• added hooks to be notified of key presses and key releases with oem codes instead of unicode code points (keyPressedRawFunction and keyReleasedRawFunction).

With these changes (and a few changes in core), it is easy to make a keyboard passthrough on the teensy 3.6.

[Macrosii]

Thanks for this the modifiersChangedFunction was exactly what I wanted and works as stated. Paul - please merge if you have time.

[gdsports]

The reportReaderFunction works as described. This makes it very easy to create a keyboard pass through/proxy.

[cyberluke]

Why is it still open? Merge it to master please.