Segment layering & effect blending improvements

- Photoshop-style segment/layer blending
- return of strip ABL
- remove global LED buffer in favour of segment-local buffer
- new effect blending modes/transitions
- custom palettes moved out of WS2812FX class
- increased limits (matrix size, LED RAM)
- added "rainbow"-mode colorwheel
- replaced palettes with gamma unmodified ones
- move gamma adjustment to last step before sending to LEDs
- Segment & WS2812FX class reorganisation (mutable members, reordered members, protected members)

wled00/wled_eeprom.cpp

@@ -225,7 +225,7 @@ void loadSettingsFromEEPROM()
   if (lastEEPROMversion > 7)
   {
     //strip.paletteFade  = EEPROM.read(374);
-    strip.paletteBlend = EEPROM.read(382);
+    paletteBlend = EEPROM.read(382);
 
     for (int i = 0; i < 8; ++i)
     {