add read/only pin logic and check

wled00/pin_manager.cpp

@@ -267,6 +267,29 @@ bool PinManagerClass::isPinOk(byte gpio, bool output) const
   return false;
 }
 
+unsigned *PinManagerClass::getReadOnlyPins()
+{
+  #ifdef READ_ONLY_PINS
+    static unsigned readOnlyPins[] = {READ_ONLY_PINS};
+  #elif
+    static unsigned readOnlyPins[] = 255;
+  #endif
+  return readOnlyPins;
+}
+
+bool PinManagerClass::isReadOnlyPin(byte gpio)
+{
+  const unsigned* pins = PinManagerClass::getReadOnlyPins();
+  const unsigned numPins = sizeof(pins) / sizeof(pins[0]);
+
+  for (unsigned i = 0; i < numPins; i++) {
+    if (pins[i] == gpio) {
+      return true;
+    }
+  }
+  return false;
+}
+
 PinOwner PinManagerClass::getPinOwner(byte gpio) const
 {
   if (!isPinOk(gpio, false)) return PinOwner::None;