Much renaming and refreshing of RBE

rustbyexample/variable_bindings.d/declare.rs

@@ -0,0 +1,19 @@
+fn main() {
+    let a_binding;
+
+    {
+        let x = 2;
+
+        a_binding = x * x;
+    }
+
+    println!("a binding: {}", a_binding);
+
+    let another_binding;
+
+    //println!("another binding: {}", another_binding);
+
+    another_binding = 1;
+
+    println!("another binding: {}", another_binding);
+}