UART with sideboards works + major refactoring

► the mainboard can now send and receive Serial data from the sideboards
► heavy refactored the `main.c`. It was becoming too large to manage... Therefore, `util.c` and `util.h` was created
► added new functionality for `VARIANT_HOVERCAR` and variants with `CONTROL_ADC` in general:
- ADC limits auto-calibration mode (long press of the power button) - calibration will not be lost at power-off
- Max Current and Max Speed adjustment mode (long press followed by a short press of the power button) - calibration will not be lost at power-off
- added one sideboard functionality:
         - LEDs are used to display battery level,  Motor Enable, Errors, Reverse driving, Braking.
         - Photo sensors are used as push buttons: One for changing Control Mode, One for Activating/Deactivating the Field Weakening on the fly

Src/control.c

@@ -114,12 +114,12 @@ void Nunchuk_Read(void) {
     timeout = 0;
   }
 
-#ifndef TRANSPOTTER
-  if (timeout > 3) {
-    HAL_Delay(50);
-    Nunchuk_Init();
-  }
-#endif
+  #ifndef TRANSPOTTER
+    if (timeout > 3) {
+      HAL_Delay(50);
+      Nunchuk_Init();
+    }
+  #endif
 
   //setScopeChannel(0, (int)nunchuk_data[0]);
   //setScopeChannel(1, (int)nunchuk_data[1]);