Use a custom platformio py file to always set build version

platformio.ini

@@ -19,16 +19,17 @@ default_envs = tbeam # lora-relay-v1 # nrf52840dk-geeksville # linux # or if you
 ; The following environment variables must be set in the shell if you'd like to override them.
 ; They are used in this ini file as systenv.VARNAME, so in your shell do export "VARNAME=fish"
 ; COUNTRY (default US), i.e. "export COUNTRY=EU865"
-; APP_VERSION (default emptystring)
 ; HW_VERSION (default emptystring)
 
 [env]
 
+; note: APP_VERSION now comes from bin/version.json
+extra_scripts = bin/platformio-custom.py 
+
 ; note: we add src to our include search path so that lmic_project_config can override
 ; FIXME: fix lib/BluetoothOTA dependency back on src/ so we can remove -Isrc
 build_flags = -Wno-missing-field-initializers -Isrc -Isrc/mesh -Isrc/gps -Ilib/nanopb/include -Wl,-Map,.pio/build/output.map 
   -DHW_VERSION_${sysenv.COUNTRY}
-  -DAPP_VERSION=${sysenv.APP_VERSION}
   -DHW_VERSION=${sysenv.HW_VERSION}
   -DUSE_THREAD_NAMES
   -DTINYGPSPLUS_OPTION_NO_CUSTOM_FIELDS