lay groundwork for a possible future architecture (#1571)

* lay groundwork for a possible future architecture

* switch from feature opt-out to feature opt-in

* lay groundwork for a possible future architecture

* switch from feature opt-out to feature opt-in

* fix USE_RTC in variant.h for rak4631_epaper and t-echo

* ensure Screen.h is not included without configuration.h

Co-authored-by: Peter Lawrence <12226419+majbthrd@users.noreply.github.com>
Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

variants/t-echo/variant.h

@@ -139,7 +139,6 @@ External serial flash WP25R1635FZUIL0
 // #define LORA_DISABLE_SENDING // Define this to disable transmission for testing (power testing etc...)
 
 // #undef SX126X_CS
-// #define USE_SIM_RADIO // define to not use the lora radio hardware at all
 
 /*
  * eink display pins
@@ -157,7 +156,7 @@ External serial flash WP25R1635FZUIL0
 // FIXME - I think this is actually just the board power enable - it enables power to the CPU also 
 #define PIN_EINK_PWR_ON (0 + 12)
 
-#define HAS_EINK
+#define USE_EINK
 
 // No screen wipes on eink
 #define SCREEN_TRANSITION_MSECS 0
@@ -220,6 +219,8 @@ External serial flash WP25R1635FZUIL0
 #define ADC_MULTIPLIER VBAT_DIVIDER_COMP 
 #define VBAT_RAW_TO_SCALED(x) (REAL_VBAT_MV_PER_LSB * x)
 
+#define HAS_RTC 1
+
 #ifdef __cplusplus
 }
 #endif