Add wxUILocale::FromTag() helper

This is exactly the same as wxUILocale(wxLocaleIdent::FromTag()) but
shorter.

interface/wx/uilocale.h

@@ -99,6 +99,18 @@ public:
      */
     static const wxUILocale& GetCurrent();
 
+    /**
+        Creates the local corresponding to the given language tag.
+
+        This is exactly equivalent to using wxUILocale constructor with
+        the locale identifier returned by wxLocaleIdent::FromTag(), but
+        shorter.
+
+        See wxLocaleIdent::FromTag() for more information about the syntax of
+        the @a tag string.
+     */
+    static wxUILocale FromTag(const wxString& tag);
+
     /**
         Creates the locale corresponding to the given locale identifier.