Fix bulb address calculation when there are more than 2 strings in a

group.

Author: gsgeschke

G35StringGroup.cpp

@@ -35,9 +35,12 @@ uint16_t G35StringGroup::get_light_count() {
 void G35StringGroup::set_color(uint8_t bulb, uint8_t intensity, color_t color) {
   uint8_t string = 0;
   while (bulb >= string_offsets_[string] && string < string_count_) {
-    bulb -= string_offsets_[string++];
+    string++;
   }
   if (string < string_count_) {
+    if (string > 0) {
+      bulb -= string_offsets_[string - 1];
+    }
     strings_[string]->set_color(bulb, intensity, color);
   } else {
     // A program is misbehaving.