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.h

@@ -602,6 +602,8 @@ WLED_GLOBAL bool wasConnected _INIT(false);
 
 // color
 WLED_GLOBAL byte lastRandomIndex _INIT(0);        // used to save last random color so the new one is not the same
+WLED_GLOBAL std::vector<CRGBPalette16> customPalettes;  // custom palettes
+WLED_GLOBAL uint8_t paletteBlend _INIT(0);        // determines bending and wrapping of palette: 0: blend, wrap if moving (SEGMENT.speed>0); 1: blend, always wrap; 2: blend, never wrap; 3: don't blend or wrap
 
 // transitions
 WLED_GLOBAL uint8_t       blendingStyle            _INIT(0);      // effect blending/transitionig style
@@ -612,6 +614,7 @@ WLED_GLOBAL unsigned long transitionStartTime;
 WLED_GLOBAL bool          jsonTransitionOnce       _INIT(false);  // flag to override transitionDelay (playlist, JSON API: "live" & "seg":{"i"} & "tt")
 WLED_GLOBAL uint8_t       randomPaletteChangeTime  _INIT(5);      // amount of time [s] between random palette changes (min: 1s, max: 255s)
 WLED_GLOBAL bool          useHarmonicRandomPalette _INIT(true);   // use *harmonic* random palette generation (nicer looking) or truly random
+WLED_GLOBAL bool          useRainbowWheel          _INIT(false);  // use "rainbow" color wheel instead of "spectrum" color wheel
 
 // nightlight
 WLED_GLOBAL bool nightlightActive _INIT(false);