Added interrupt-driven non-blocking ADC read. First step in increasing loop frequencies

lib/ADC.hpp

@@ -0,0 +1,11 @@
+#ifndef ADC_H
+#define ADC_H
+
+#include <Arduino.h>
+#include <util/atomic.h>
+
+extern volatile uint16_t adc_results[];
+
+void setupADC();
+
+#endif