Changing array to be an associative array so that the Name function can work with non-sequential enums as well as those beginning at something other than zero. (#5151)

Also including the resulting changes in php files.

tests/union_vector/Character.php

@@ -12,13 +12,13 @@ class Character
     const Unused = 6;
 
     private static $names = array(
-        "NONE",
-        "MuLan",
-        "Rapunzel",
-        "Belle",
-        "BookFan",
-        "Other",
-        "Unused",
+        Character::NONE=>"NONE",
+        Character::MuLan=>"MuLan",
+        Character::Rapunzel=>"Rapunzel",
+        Character::Belle=>"Belle",
+        Character::BookFan=>"BookFan",
+        Character::Other=>"Other",
+        Character::Unused=>"Unused",
     );
 
     public static function Name($e)