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>

src/modules/AdminModule.cpp

@@ -6,7 +6,7 @@
 #include "configuration.h"
 #include "main.h"
 
-#ifdef PORTDUINO
+#ifdef ARCH_PORTDUINO
 #include "unistd.h"
 #endif
 
@@ -110,7 +110,7 @@ bool AdminModule::handleReceivedProtobuf(const MeshPacket &mp, AdminMessage *r)
         break;
     }
 
-#ifdef PORTDUINO
+#ifdef ARCH_PORTDUINO
     case AdminMessage_exit_simulator_tag:
         DEBUG_MSG("Exiting simulator\n");
         _exit(0);