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/udp.cpp

@@ -232,11 +232,12 @@ void handleNotifications()
   if (!udpConnected) return;
 
   bool isSupp = false;
-  size_t packetSize = notifierUdp.parsePacket();
-  if (!packetSize && udp2Connected) {
+  int packetSize = notifierUdp.parsePacket();    // WLEDMM function returns int, not size_t
+  if ((packetSize < 1) && udp2Connected) {
     packetSize = notifier2Udp.parsePacket();
     isSupp = true;
   }
+  if (packetSize < 1) packetSize = 0; // WLEDMM
 
   //hyperion / raw RGB
   if (!packetSize && udpRgbConnected) {