Forgot to add version files to the project. Silly me.

version.cpp

@@ -0,0 +1,4 @@
+#include "version.h"
+
+const char VERSION_STRING_PRIVATE [] PROGMEM = "R1.1.1";
+const char* const VERSION_STRING = VERSION_STRING_PRIVATE;

version.h

@@ -0,0 +1,9 @@
+#pragma once
+
+#include <avr/pgmspace.h>
+
+/*
+ * VERSION_STRING is a PROGMEM string, so extract it before use, e.g.
+ *      strncpy_P(char_buffer_out,VERSION_STRING,size_of_char_buffer_out);
+ */
+extern const char* const VERSION_STRING;