Platformio: further refactoring and bug fixing

platformio:
- min and max as postfix instead of prefix
- add common_mm entry for MM build_flags and lib_deps
- add esp32_4MB_V4_max_base entry for V4

const.h and FX_(2D)fcn.cpp: add IRAM_ATTR_YN to switch off if not esp32 (esp8266 not enough iram for this)

json.cpp: start stop compatibility only if 2D not disabled

wled00/const.h

@@ -431,4 +431,12 @@
   #define HW_PIN_CSSPI SS
 #endif
 
+// WLEDSR: IRAM_ATTR for 8266 causes error: section `.text1' will not fit in region `iram1_0_seg'
+//         error only in MM, not in upstream... tbd: find out why
+#ifdef ARDUINO_ARCH_ESP32
+  #define IRAM_ATTR_YN IRAM_ATTR
+#else
+  #define IRAM_ATTR_YN
+#endif
+
 #endif