updated Segment::color_from_palette

- gamma correction only where needed
- paletteIndex should be uint8_t (it is only used as that)
note: integrating the new `ColorFromPaletteWLED()` into this would require  a whole lot of code rewrite and would result in more color conversions from 32bit to CRGB. It would be really useful only if CRGB is replaced with native 32bit colors.

wled00/FX_fcn.cpp

@@ -1181,18 +1181,21 @@ uint32_t Segment::color_wheel(uint8_t pos) const {
  * @returns Single color from palette
  */
 uint32_t Segment::color_from_palette(uint16_t i, bool mapping, bool wrap, uint8_t mcol, uint8_t pbri) const {
-  uint32_t color = gamma32(currentColor(mcol));
-
+  
+  uint32_t color = currentColor(mcol);
   // default palette or no RGB support on segment
-  if ((palette == 0 && mcol < NUM_COLORS) || !_isRGB) return (pbri == 255) ? color : color_fade(color, pbri, true);
+  if ((palette == 0 && mcol < NUM_COLORS) || !_isRGB) {
+    color = gamma32(color);
+    return (pbri == 255) ? color : color_fade(color, pbri, true);
+  }
 
-  unsigned paletteIndex = i;
+  uint8_t paletteIndex = i;
   if (mapping && virtualLength() > 1) paletteIndex = (i*255)/(virtualLength() -1);
   // paletteBlend: 0 - wrap when moving, 1 - always wrap, 2 - never wrap, 3 - none (undefined)
   if (!wrap && strip.paletteBlend != 3) paletteIndex = scale8(paletteIndex, 240); //cut off blend at palette "end"
   CRGB fastled_col = ColorFromPalette(_currentPalette, paletteIndex, pbri, (strip.paletteBlend == 3)? NOBLEND:LINEARBLEND); // NOTE: paletteBlend should be global
 
-  return RGBW32(fastled_col.r, fastled_col.g, fastled_col.b, W(color));
+  return RGBW32(fastled_col.r, fastled_col.g, fastled_col.b, gamma8(W(color)));
 }