adjusting settings and slide_model.rs

These are trying to get more code written in Rust rather than c++. Not
there yet, but I need to sync these to another machine.

build.rs

@@ -6,5 +6,6 @@ fn main() {
         .file("src/rust/settings.rs")
         .file("src/rust/file_helper.rs")
         .file("src/rust/slide_obj.rs")
+        .file("src/rust/slide_model.rs")
         .build();
 }