Remove iteration_context, parameters_context, and most of bin.rs.

Since I'm changing a pretty core concept of the renderer, I'm going to be rebuilding it piece by piece. In the interest of being able to rapidly change things and check if they are valid through compilation, I need to eliminate most of the old code so I do not have that weighing me down.

src/renderer/mod.rs

@@ -4,8 +4,8 @@ mod breadcrumb_tree;
 mod context_element;
 mod errors;
 mod inline_partial_tree;
-mod iteration_context;
-mod parameters_context;
+// mod iteration_context;
+// mod parameters_context;
 mod renderer;
 mod tree_walking;
 mod walking;