Replace lalrpop-intern with string_cache

string_cache::Atom does not implement Copy, so the majority of the
changes are adding calls to clone.

Author: AzureMarker

Cargo.lock

@@ -16,7 +16,6 @@ bench = []
 [dependencies]
 docopt = "1.0.0"
 itertools = "0.9.0"
-lalrpop-intern = "0.15.1"
 rustyline = "1.0"
 salsa = "0.10.0"
 serde = "1.0"

Cargo.toml

@@ -10,7 +10,7 @@ edition = "2018"
 publish = false
 
 [dependencies]
-lalrpop-intern = "0.15.1"
+string_cache = "0.8.0"
 salsa = "0.10.0"
 
 chalk-macros = { version = "0.10.1-dev", path = "../chalk-macros" }

chalk-integration/Cargo.toml

@@ -9,12 +9,12 @@ use chalk_ir::{
     Goal, GoalData, LifetimeData, Parameter, ParameterData, ParameterKind, ProgramClause,
     ProgramClauseData, QuantifiedWhereClause, StructId, TyData, UniverseIndex,
 };
-use lalrpop_intern::InternedString;
 use std::fmt;
 use std::fmt::Debug;
 use std::sync::Arc;
+use string_cache::DefaultAtom;
 
-pub type Identifier = InternedString;
+pub type Identifier = DefaultAtom;
 
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct RawId {