Switch back to a standard hashmap to prevent crashes

src/main/java/com/cricketcraft/chisel/carving/GroupList.java

@@ -4,7 +4,6 @@ import java.util.Collection;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
-import java.util.Map;
 import java.util.Set;
 
 import net.minecraft.block.Block;
@@ -13,7 +12,6 @@ import org.apache.commons.lang3.tuple.Pair;
 
 import com.cricketcraft.chisel.api.carving.ICarvingGroup;
 import com.cricketcraft.chisel.api.carving.ICarvingVariation;
-import com.google.common.collect.HashBiMap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 
@@ -79,7 +77,7 @@ public class GroupList implements Set<ICarvingGroup> {
 	}
 
 	private HashMap<String, ICarvingGroup> groups = Maps.newHashMap();
-	private HashBiMap<VariationWrapper, ICarvingGroup> lookup = HashBiMap.create();
+	private HashMap<VariationWrapper, ICarvingGroup> lookup = Maps.newHashMap();
 
 	@Override
 	public int size() {
@@ -133,11 +131,10 @@ public class GroupList implements Set<ICarvingGroup> {
 	@Override
 	public boolean remove(Object o) {
 		if (o instanceof ICarvingGroup) {
-			Map<ICarvingGroup, VariationWrapper> reverse = lookup.inverse();
 			List<VariationWrapper> toRemove = Lists.newArrayList();
-			for (ICarvingGroup g : reverse.keySet()) {
-				if (g.getName().equals(((ICarvingGroup) o).getName())) {
-					toRemove.add(reverse.get(g));
+			for (VariationWrapper v : lookup.keySet()) {
+				if (lookup.get(v).getName().equals(((ICarvingGroup) o).getName())) {
+					toRemove.add(v);
 				}
 			}
 			for (VariationWrapper v : toRemove) {