HID needs to wait until initialized

[NicoHood]

We need something similar to while(!Serial) just for HID. In this example StartupHID never appears. You need to add a 1-2s delay first.

#include "HID-Project.h"

void setup() {
  while(!HID);
  Keyboard.begin();
  Keyboard.println("StartupHID"); 

  // initialize digital pin 13 as an output.
  pinMode(13, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(13, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);              // wait for a second
  digitalWrite(13, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);              // wait for a second
}

[NicoHood]

Fixed with 60bd43e
Similar approach:
arduino/Arduino#3624

Still not perfect, but at least a solution. Should we also add this check the the HID send function?

[NicoHood]

HID_::operator bool() {
    if(USBDevice.configured()){
        delay(10);
        return true;
    }
    else{
        return false;
    }
}

TODO after the update