some effect optimizations

* getpixelcolor: attribute pure - it reads memory, but does not write
* some optimizations for SEGMENT.blur() and SEGMENT.fadeToBlackBy()

* FX.c:pp remove double calls to blur() and fade_out()
* FX.cpp: SEGMENT.setUpLeds() added to effects, to enable LED buffering (safe some time because getPixelColor does not need to access NeopixelBus)

* a few other optimizations to safe time and avoid "expensive" operations
* set I2C bus speed to 400kHz (default is 100Khz)

* a few other small optimizations and tweaks
* pio: esp32 V4 builds use "patch5" toolchain version, which contains a few bugfixes especially for memory management.

wled00/pin_manager.cpp

@@ -588,7 +588,11 @@ bool PinManagerClass::joinWire(int8_t pinSDA, int8_t pinSCL) {
   }
 
   #ifdef ARDUINO_ARCH_ESP32
+  #if defined(WLEDMM_FASTPATH)  // wledMM set I2C to 400Khz, to minimize I2C communication delays
+    wireIsOK = Wire.begin(pinSDA, pinSCL, 400000UL);  // this will fail if wire is already running
+  #else
     wireIsOK = Wire.begin(pinSDA, pinSCL);  // this will fail if wire is already running
+  #endif
   #else
     Wire.begin(pinSDA, pinSCL);  // returns void on 8266
   #endif