0.4.3 Fix #92: omg - for the last couple of weeks the official builds were

all using US frequencies.  This build fixes this (and makes the build
system cleaner in general).

If you are building your own builds in the IDE you'll need to start
setting an environment variable called COUNTRY to your two letter
country code (or leave unset to get US frequencies).  See new comment
in platformio.ini.

platformio.ini

@@ -12,9 +12,14 @@
 default_envs = tbeam
 
 [common]
-; default to a US frequency range, change it as needed for your region and hardware (CN, JP, EU433, EU865)
-hw_version = US
+; common is not currently used
 
+; REQUIRED environment variables - if not set the specified default will be sued
+; 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"
+; HW_VERSION (default US)
+; APP_VERSION (default emptystring)
+; HW_VERSION (default emptystring)
 
 [env]
 platform = espressif32
@@ -26,7 +31,11 @@ board_build.partitions = partition-table.csv
 
 ; 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/rf95 -Os -Wl,-Map,.pio/build/output.map -DAXP_DEBUG_PORT=Serial -DHW_VERSION_${common.hw_version}
+build_flags = -Wno-missing-field-initializers -Isrc -Isrc/rf95 -Os -Wl,-Map,.pio/build/output.map 
+  -DAXP_DEBUG_PORT=Serial 
+  -DHW_VERSION_${sysenv.COUNTRY}
+  -DAPP_VERSION=${sysenv.APP_VERSION}
+  -DHW_VERSION=${sysenv.HW_VERSION}
 
 ; not needed included in ttgo-t-beam board file
 ; also to use PSRAM https://docs.platformio.org/en/latest/platforms/espressif32.html#external-ram-psram