Lots of changes and optimizations

- add reverse encoder menu option and save state
- improve usage of EncoderDir in ISR with pointer to instance and static isr() method.
- reduce u8g2 memory usage by using single page buffer
- improve save state behavor by using a mutex flag and update check with debounce in main loop
- make saving to EEPROM safer by wrapping put calls with noInterrupts()

gravity.h

@@ -29,7 +29,7 @@ class Gravity {
     // Polling check for state change of inputs and outputs.
     void Process();
 
-    U8G2_SSD1306_128X64_NONAME_2_HW_I2C display;  // OLED display object.
+    U8G2_SSD1306_128X64_NONAME_1_HW_I2C display;  // OLED display object.
     Clock clock;                                  // Clock source wrapper.
     DigitalOutput outputs[OUTPUT_COUNT];          // An array containing each Output object.
     EncoderDir encoder;                           // Rotary encoder with button instance