num of LEDs needs to be modulo 3

there is a bug in:
for (int q=0; q < 3; q++) {
            for (int i=0; i < NUM_LEDS; i=i+3) {
                int pos = i+q;
                leds[pos] = c; 
if NUM_LEDS is 50 you end up in  48 +   2 =  50 for i = 48 q = 2
which writes to an position outside the array or cause an exception 
you better check for (i+q) < NUM_LEDS

this limitation / bug is inherried from examples
