Fix .ydd export/import with unsolved hashes

When a drawable hash was unknown, it kept the "filename.#dd" name so
exporting to XML lost the hash and importing it back created a broken
file.

Now if the hash is unknown, the name is set to `hash_1234ABCD`, and XML
import checks for `hash_`.

CodeWalker.Core/GameFiles/Resources/Drawable.cs

@@ -5847,7 +5847,7 @@ namespace CodeWalker.GameFiles
                     var d = new Drawable();
                     d.ReadXml(inode, ddsfolder);
                     drawables.Add(d);
-                    drawablehashes.Add(JenkHash.GenHash(d.Name));//TODO: check this!
+                    drawablehashes.Add(XmlMeta.GetHash(d.Name));
                 }
             }