Lots of improvements.

* Better script names and grammar fix.
* Bump Rust
* Enforce more lints.
* Improve few struct definitions by removing box.
* Many minor implementation improvements.

src/irgen/mod.rs

@@ -4,10 +4,10 @@ use lang_c::ast::*;
 
 use crate::*;
 
-#[derive(Default, Debug)]
+#[derive(Default, Clone, Copy, Debug)]
 pub struct Irgen {}
 
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Clone, Copy, Debug)]
 pub struct IrgenError {}
 
 impl fmt::Display for IrgenError {