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/mesh/mesh-pb-constants.cpp

@@ -32,6 +32,7 @@ bool pb_decode_from_bytes(const uint8_t *srcbuf, size_t srcbufsize, const pb_msg
     }
 }
 
+#ifdef FSCom
 /// Read from an Arduino File
 bool readcb(pb_istream_t *stream, uint8_t *buf, size_t count)
 {
@@ -59,6 +60,7 @@ bool writecb(pb_ostream_t *stream, const uint8_t *buf, size_t count)
     // DEBUG_MSG("writing %d bytes to protobuf file\n", count);
     return file->write(buf, count) == count;
 }
+#endif
 
 bool is_in_helper(uint32_t n, const uint32_t *array, pb_size_t count)
 {