Configurable Rainbow Swirl range (#4376)

* Configurable Rainbow Swirl range

This allows tweaking of the rainbow effect to
 get different effects on keyboards with varied
 LED layouts. We found the value 1950 works on
 the RGBKB.net Sol to get a cool striped effect
 across the keyboard.

* Document RGBLIGHT_RAINBOW_SWIRL_RANGE

* Better wording for the documentation

docs/feature_rgblight.md

@@ -122,6 +122,7 @@ The following options can be used to tweak the various animations:
 |`RGBLIGHT_EFFECT_KNIGHT_LED_NUM`    |`RGBLED_NUM` |The number of LEDs to have the "Knight" animation travel                             |
 |`RGBLIGHT_EFFECT_CHRISTMAS_INTERVAL`|`1000`       |How long to wait between light changes for the "Christmas" animation, in milliseconds|
 |`RGBLIGHT_EFFECT_CHRISTMAS_STEP`    |`2`          |The number of LEDs to group the red/green colors by for the "Christmas" animation    |
+|`RGBLIGHT_RAINBOW_SWIRL_RANGE`      |`360`        |Range adjustment for the rainbow swirl effect to get different swirls                |
 
 You can also modify the speeds that the different modes animate at:
 

quantum/rgblight.c

@@ -679,6 +679,10 @@ void rgblight_effect_rainbow_mood(uint8_t interval) {
 #endif
 
 #ifdef RGBLIGHT_EFFECT_RAINBOW_SWIRL
+#ifndef RGBLIGHT_RAINBOW_SWIRL_RANGE
+  #define RGBLIGHT_RAINBOW_SWIRL_RANGE 360
+#endif
+
 __attribute__ ((weak))
 const uint8_t RGBLED_RAINBOW_SWIRL_INTERVALS[] PROGMEM = {100, 50, 20};
 
@@ -692,7 +696,7 @@ void rgblight_effect_rainbow_swirl(uint8_t interval) {
   }
   last_timer = timer_read();
   for (i = 0; i < RGBLED_NUM; i++) {
-    hue = (360 / RGBLED_NUM * i + current_hue) % 360;
+    hue = (RGBLIGHT_RAINBOW_SWIRL_RANGE / RGBLED_NUM * i + current_hue) % 360;
     sethsv(hue, rgblight_config.sat, rgblight_config.val, (LED_TYPE *)&led[i]);
   }
   rgblight_set();