schema tree BUGFIX free based identity array

Fixes #110
diff --git a/src/tree_schema.c b/src/tree_schema.c
index fec568b..d4e2892 100644
--- a/src/tree_schema.c
+++ b/src/tree_schema.c
@@ -1256,8 +1256,12 @@
         free(type->info.uni.types);
         break;
 
+    case LY_TYPE_IDENT:
+        free(type->info.ident.ref);
+        break;
+
     default:
-        /* nothing to do for LY_TYPE_IDENT, LY_TYPE_INST, LY_TYPE_BOOL, LY_TYPE_EMPTY */
+        /* nothing to do for LY_TYPE_INST, LY_TYPE_BOOL, LY_TYPE_EMPTY */
         break;
     }
 }