'document' hardware config variables

src/EuglenaApplet.java

@@ -7,7 +7,10 @@ public class EuglenaApplet extends PApplet {
         This applet draws the main window and menu
      */
 
+    // Camera capture mode. See the comments in Camera.java for an explanation.
     final int cameraMode = 8;
+
+    // Which arduino to use.
     final int whichArduino = 0;
 
     // Hardware