Improvement to setPixelColorXY and some flash optimisations

- changes to `setPixelColorXY` give an extra FPS, some checks and the loops are only done when needed, additional function call is still faster (force inlining it gives negligible speed boost but eats more flash)
- commented out the unused `boxBlur` function
- code size improvemnts (also faster) in `moveX()` and `moveY()` by only copying whats required and avoiding code duplications
- consolidated the `blur()` functions by enabling asymmetrical blur2D() to replace `blurRow` and `blurCol`
- compiler warning fixes (explicit unsigned casts)

wled00/FX_fcn.cpp

@@ -1146,7 +1146,7 @@ void Segment::blur(uint8_t blur_amount, bool smear) {
 #ifndef WLED_DISABLE_2D
   if (is2D()) {
     // compatibility with 2D
-    blur2D(blur_amount, smear);
+    blur2D(blur_amount, blur_amount, smear); // symmetrical 2D blur
     //box_blur(map(blur_amount,1,255,1,3), smear);
     return;
   }