Move tube to separate file

tube.ino

@@ -0,0 +1,22 @@
+#include "grove_alphanumeric_display.h"
+
+Seeed_Digital_Tube tube;
+
+void initTube() {
+  // Wire initialized by temperature sensor
+  tube.setTubeType(TYPE_4, TYPE_4_DEFAULT_I2C_ADDR);
+  tube.setBrightness(15);
+  tube.setBlinkRate(BLINK_OFF);
+  tube.setPoint(true,true);  
+}
+
+void updateTube() {
+  char tube_str[5];
+
+  if (countdown <= 0)
+    sprintf(tube_str, "%4u", (unsigned int) (temperature * 100.0));
+  else
+    sprintf(tube_str, "%4u", countdown);
+
+  tube.displayString(tube_str);
+}