context UPDATE new flag for enabling features of imports

Allow enabling all features of implemented
imports when loading a new module.
diff --git a/src/schema_compile_amend.c b/src/schema_compile_amend.c
index 9353be6..92d69d2 100644
--- a/src/schema_compile_amend.c
+++ b/src/schema_compile_amend.c
@@ -2195,6 +2195,7 @@
     struct lys_module *m;
     struct lysp_submodule *submod;
     struct lysp_node_augment *aug;
+    const char **imp_f, *all_f[] = {"*", NULL};
     uint32_t i;
     struct ly_set mod_set = {0}, set = {0};
 
@@ -2290,7 +2291,8 @@
 
         if (!m->implemented) {
             /* implement the target module */
-            r = lys_implement(m, NULL, unres);
+            imp_f = (mod->ctx->flags & LY_CTX_ENABLE_IMP_FEATURES) ? all_f : NULL;
+            r = lys_implement(m, imp_f, unres);
             if (r == LY_ERECOMPILE) {
                 /* implement all the modules right away to save possible later recompilation */
                 ret = r;