Add TEMP_THRESHOLD env variable.

User can set a variable above which T will be shown in colour
if the display supports it.

inkyshot/update-display.py

@@ -272,6 +272,11 @@ def celcius_to_fahrenheit(temp):
 # Temperature scale
 SCALE = 'F' if "SCALE" in os.environ and os.environ["SCALE"] == 'F' else 'C'
 
+# Temperature threshold above which T is displayed in colour
+TEMP_THRESHOLD = 25 if SCALE == 'C' else celcius_to_fahrenheit(25)
+if "TEMP_THRESHOLD" in os.environ:
+    TEMP_THRESHOLD = os.environ['TEMP_THRESHOLD']
+
 # Locale formatting of date
 LOCALE = os.environ["LOCALE"] if "LOCALE" in os.environ else 'en'