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.cpp

@@ -529,6 +529,7 @@ void WLED::setup()
 void WLED::beginStrip()
 {
   // Initialize NeoPixel Strip and button
+  strip.setTransition(0); // temporarily prevent transitions to reduce segment copies
   strip.finalizeInit(); // busses created during deserializeConfig() if config existed
   strip.makeAutoSegments();
   strip.setBrightness(0);
@@ -557,6 +558,8 @@ void WLED::beginStrip()
     applyPreset(bootPreset, CALL_MODE_INIT);
   }
 
+  strip.setTransition(transitionDelayDefault);  // restore transitions
+
   // init relay pin
   if (rlyPin >= 0) {
     pinMode(rlyPin, rlyOpenDrain ? OUTPUT_OPEN_DRAIN : OUTPUT);