More work on console I/O and minor fixes

luprex/core/cpp/world-diffxmit.cpp

@@ -1,4 +1,5 @@
 #include "world.hpp"
+#include <iostream>
 
 util::IdVector World::get_visible_union(int64_t actor_id, World *master) {
     return util::sort_union_id_vectors(
@@ -263,7 +264,13 @@ void World::diff_tanclass(int64_t actor_id, World *master, StreamBuffer *xsb) {
 }
 
 void World::patch_source(StreamBuffer *sb) {
-    source_db_.patch(sb);
+    bool modified = source_db_.patch(sb);
+    if (modified) {
+        std::string errs = source_db_.rebuild();
+        // TODO: I don't currently have any good place to send the
+        // error messages.  This is a stopgap.
+        std::cerr << errs;
+    }
 }
 
 void World::diff_source(World *master, StreamBuffer *sb) {