parser FEATURE added collision check for grouping

Collision checking of names is similar to typedef checking.
diff --git a/src/tree_schema.c b/src/tree_schema.c
index 4603fb8..3c95a90 100644
--- a/src/tree_schema.c
+++ b/src/tree_schema.c
@@ -1569,7 +1569,7 @@
 
     /* check name collisions */
     LY_CHECK_GOTO(ret = lysp_check_dup_typedefs(pctx, mod->parsed), cleanup);
-    /* TODO groupings */
+    LY_CHECK_GOTO(ret = lysp_check_dup_groupings(pctx, mod->parsed), cleanup);
     LY_CHECK_GOTO(ret = lysp_check_dup_features(pctx, mod->parsed), cleanup);
     LY_CHECK_GOTO(ret = lysp_check_dup_identities(pctx, mod->parsed), cleanup);