Fixes for FFI.

src/static_data/libraries/data_library.rs

@@ -33,6 +33,11 @@ pub trait DataLibrary<'a, T: 'a> {
         self.map().get::<u32>(&key)
     }
 
+    /// Gets a value from the library by the index where it is stored.
+    fn get_key_by_index(&'a self, index: usize) -> Option<&StringKey> {
+        self.map().get_index(index).map(|a| a.0)
+    }
+
     /// Gets the amount of values in the library.
     fn len(&self) -> usize {
         self.map().len()