mutiple RGBW leds support for DMX control

RGBW leds can be individually adressed through E1.31 control.
-Added option 'Multi RGBW' to the settings
-Modified e131.cpp accordingly
-Tuned other parameters to make it work

wled00/data/settings_sync.htm

@@ -64,6 +64,7 @@ DMX mode:
 <option value=3>Effect</option>
 <option value=4>Multi RGB</option>
 <option value=5>Dimmer + Multi RGB</option>
+<option value=6>Multi RGBW</option>
 </select><br>
 <a href="https://github.com/Aircoookie/WLED/wiki/E1.31-DMX" target="_blank">E1.31 info</a><br>
 Timeout: <input name="ET" type="number" min="1" max="65000" required> ms<br>