Implement url en/decoding

src/opds_handler.c

@@ -49,7 +49,7 @@ static Noh_String create_feed_response(Library_Entry self_path, SV url, Library_
 static enum MHD_Result handle_opds(struct MHD_Connection *connection, SV url, Settings settings, SV username) {
     noh_arena_save(&temp);
     Noh_String fs_path = build_path(false, false, &settings.base_path, &username, &url);
-    noh_string_replace(&fs_path, '+', ' ');
+    url_decode(&fs_path);
     Noh_String fs_path_cstr = fs_path;
     noh_string_append_null(&fs_path_cstr);