Move openURL function and two strings from public/ to mod/.

Use it for the mod author website now.
Use it for the terms links next, refs #5257, D1627.

This was SVN commit r21889.

binaries/data/mods/mod/gui/common/functions_msgbox.js

@@ -46,3 +46,16 @@ function messageBox(mbWidth, mbHeight, mbMessage, mbTitle, mbButtonCaptions, mbB
 		"callback": mbBtnCode && "messageBoxCallbackFunction"
 	});
 }
+
+function openURL(url)
+{
+	Engine.OpenURL(url);
+
+	messageBox(
+		600, 200,
+		sprintf(
+			translate("Opening %(url)s\n in default web browser. Please wait…"),
+			{ "url": url }
+		),
+		translate("Opening page"));
+}

binaries/data/mods/mod/gui/modmod/modmod.js

@@ -395,5 +395,5 @@ function visitModWebsite()
 	if (!url.startsWith("http://") && !url.startsWith("https://"))
 		url = "http://" + url;
 
-	Engine.OpenURL(url);
+	openURL(url);
 }

binaries/data/mods/public/gui/common/functions_global_object.js

@@ -1,17 +1,3 @@
-function openURL(url)
-{
-	Engine.OpenURL(url);
-
-	messageBox(
-		600, 200,
-		sprintf(
-			translate("Opening %(url)s\n in default web browser. Please wait…"),
-			{ "url": url }
-		),
-		translate("Opening page")
-	);
-}
-
 function updateCounters()
 {
 	let counters = [];