Update ICU to 58.3

- This adds the new Japanese ascension era (Reiwa)
- This updates timezone data to 2019a
- Updated script for git instead of SVN
- Regenerated locale data

intl/icu/source/data/locales/sr.txt

@@ -1,4 +1,4 @@
-// © 2016 and later: Unicode, Inc. and others.
+// © 2016 and later: Unicode, Inc. and others.
 // License & terms of use: http://www.unicode.org/copyright.html#License
 sr{
     AuxExemplarCharacters{"[ё й щ ъ ы ь э ю я]"}
@@ -1231,6 +1231,7 @@ sr{
                     "Таишо",
                     "Шова",
                     "Хаисеи",
+                    "Реива",
                 }
             }
         }