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/ir/equiv.rs

@@ -289,7 +289,7 @@ fn is_equiv_block_exit(lhs: &BlockExit, rhs: &BlockExit, map: &HashMap<BlockId,
             if !is_equiv_operand(value, value_other, map) {
                 return false;
             }
-            if !is_equiv_arg(default.deref(), default_other.deref(), map) {
+            if !is_equiv_arg(default, default_other, map) {
                 return false;
             }
             if cases.len() != cases_other.len() {