schema parsers FEATURE processing imports and includes

So far only in parsed structures, not the compiled.
diff --git a/src/context.c b/src/context.c
index 585504c..2394faf 100644
--- a/src/context.c
+++ b/src/context.c
@@ -449,7 +449,7 @@
         }
 
         LY_ARRAY_FOR(mod->parsed->includes, u) {
-            if (!strcmp(submodule, mod->parsed->includes[u].submodule->name)) {
+            if (mod->parsed->includes[u].submodule && !strcmp(submodule, mod->parsed->includes[u].submodule->name)) {
                 inc = &mod->parsed->includes[u];
                 if (!revision) {
                     if (inc->submodule->latest_revision) {