Remove lifetime mess, replace a lot of code with Arc instead of borrows.

This cleans up the codebase massively, and allows me to maintain some semblance of sanity.

src/static_data/libraries/item_library.rs

@@ -1,3 +1,5 @@
+use std::sync::Arc;
+
 use indexmap::IndexMap;
 
 use crate::static_data::DataLibrary;
@@ -9,7 +11,7 @@ use crate::StringKey;
 #[cfg_attr(feature = "wasm", derive(unique_type_id_derive::UniqueTypeId))]
 pub struct ItemLibrary {
     /// The underlying data structure.
-    map: IndexMap<StringKey, Box<Item>>,
+    map: IndexMap<StringKey, Arc<Item>>,
 }
 
 impl ItemLibrary {
@@ -21,12 +23,12 @@ impl ItemLibrary {
     }
 }
 
-impl DataLibrary<'_, Box<Item>> for ItemLibrary {
-    fn map(&self) -> &IndexMap<StringKey, Box<Item>> {
+impl DataLibrary<'_, Item> for ItemLibrary {
+    fn map(&self) -> &IndexMap<StringKey, Arc<Item>> {
         &self.map
     }
 
-    fn get_modify(&mut self) -> &mut IndexMap<StringKey, Box<Item>> {
+    fn get_modify(&mut self) -> &mut IndexMap<StringKey, Arc<Item>> {
         &mut self.map
     }
 }