Allow misaligned pgm_read_XXX macro reads (#81)

Update the ArduinoAPI with new macros/inlines that allow accessing
values that are not naturally aligned (i.e. an int at address 0x0001).

Fixes #79

ArduinoCore-API @ b20f68b6

-Subproject commit 8f747a4a5756cbea5123b34bb7f65b043cb80c26
+Subproject commit b20f68b65c787eec78ef81762c85db999d2ce071

cores/rp2040/Arduino.h

@@ -68,6 +68,7 @@ float analogReadTemp();  // Returns core temp in Centigrade
 // PWM
 void analogWrite(pin_size_t pinNumber, int value);
 
+// Timing
 void delay(unsigned long);
 void delayMicroseconds(unsigned int us);
 unsigned long millis();