Added 'darkmode_allow' setting, which defaults to true.

'darkmode_off' will still work if set, but is deprecated.
Added 'darkmode_on' setting, which defaults to false;
if set, darkmode is turned on until the user turns it off.

webv4/lib/init.js

@@ -46,9 +46,13 @@ var defaults = {
 			if (typeof v !== 'string') return new Error('Invalid files_inline_blacklist setting ' + v);
 			return v.split(',');
 		}
-	}
+	},
+	darkmode_allow: { default: true },
+	darkmode_on: { default: false },
 };
 
+if (settings.darkmode_off) settings.darkmode_allow = false;
+
 function doError(e) {
 	log(LOG_ERROR, e);
 	http_reply.status = '500 Internal Server Error';