Allow dead code for all exercises and solutions

solutions/08_enums/enums2.rs

@@ -1,5 +1,3 @@
-#![allow(dead_code)]
-
 #[derive(Debug)]
 struct Point {
     x: u64,

solutions/10_modules/modules2.rs

@@ -1,4 +1,3 @@
-#[allow(dead_code)]
 mod delicious_snacks {
     // Added `pub` and used the expected alias after `as`.
     pub use self::fruits::PEAR as fruit;

solutions/15_traits/traits3.rs

@@ -1,5 +1,3 @@
-#![allow(dead_code)]
-
 trait Licensed {
     fn licensing_info(&self) -> String {
         "Default license".to_string()

solutions/19_smart_pointers/rc1.rs

@@ -8,7 +8,6 @@ use std::rc::Rc;
 #[derive(Debug)]
 struct Sun;
 
-#[allow(dead_code)]
 #[derive(Debug)]
 enum Planet {
     Mercury(Rc<Sun>),