Support local variable remapping (#114)

* Support local variables

* Update copyright date

src/main/java/net/fabricmc/tinyremapper/AsmRemapper.java

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2016, 2018, Player, asie
- * Copyright (c) 2018, 2021, FabricMC
+ * Copyright (c) 2018, 2023, FabricMC
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published by
@@ -135,7 +135,8 @@ public String mapMethodArg(String methodOwner, String methodName, String methodD
 	}
 
 	public String mapMethodVar(String methodOwner, String methodName, String methodDesc, int lvIndex, int startOpIdx, int asmIndex, String name) {
-		return name; // TODO: implement
+		String newName = tr.methodVarMap.get(methodOwner+"/"+MemberInstance.getMethodId(methodName, methodDesc)+lvIndex);
+		return newName != null ? newName : name;
 	}
 
 	@Override

src/main/java/net/fabricmc/tinyremapper/TinyRemapper.java

@@ -705,7 +705,7 @@ public void acceptMethodVar(Member method, int lvIndex, int startOpIdx, int asmI
 				if (method.desc == null) throw new NullPointerException("null src method desc");
 				if (dstName == null) throw new NullPointerException("null dst name");
 
-				// TODO Auto-generated method stub
+				methodVarMap.put(method.owner+"/"+MemberInstance.getMethodId(method.name, method.desc)+lvIndex, dstName);
 			}
 
 			@Override
@@ -1411,6 +1411,7 @@ public void propagate(TrMember m, String newName) {
 	final Map<String, String> classMap = new HashMap<>();
 	final Map<String, String> methodMap = new HashMap<>();
 	final Map<String, String> methodArgMap = new HashMap<>();
+	final Map<String, String> methodVarMap = new HashMap<>();
 	final Map<String, String> fieldMap = new HashMap<>();
 	final Map<MemberInstance, Set<String>> conflicts = new ConcurrentHashMap<>();
 	final Set<ClassInstance> classesToMakePublic = Collections.newSetFromMap(new ConcurrentHashMap<>());