schema CHANGE more strict recompilation rules

The general idea now is that whenever a module
is being compiled that imports any implemented
and compiled modules, the compilation is refused
and the whole context is recompiled instead.
It is connected with the following change that
will keep disabled nodes in the compiled modules
and remove them at the whole compilation end
so they can be referenced by other modules.
diff --git a/src/context.c b/src/context.c
index 7ed97c7..5ff7380 100644
--- a/src/context.c
+++ b/src/context.c
@@ -503,7 +503,7 @@
     }
 
     /* recompile */
-    LY_CHECK_RET(lys_recompile(ctx, 0));
+    LY_CHECK_RET(lys_recompile(ctx, 1));
 
     /* everything is fine, clear the flags */
     for (i = 0; i < ctx->list.count; ++i) {