Replace most uses of std::cerr with util::dprint

luprex/cpp/core/world-core.cpp

@@ -355,7 +355,7 @@ void World::update_gui(int64_t actor_id, int64_t place_id, Gui *gui) {
     Gui::store_global_pointer(L, nullptr);
     if (!msg.empty()) {
         gui->clear(0);
-        std::cerr << msg << std::endl;
+        util::dprint(msg);
         LS.result();
         return;
     }
@@ -376,10 +376,7 @@ void World::update_source(const util::LuaSourceVec &source) {
     source_db_.update(source);
     assert(stack_is_clear());
     eng::string errs = source_db_.rebuild();
-    // I don't have a good place to send the error messages right
-    // now.  The engine needs a catch-all place to send errors that
-    // occur at unexpected times.
-    std::cerr << errs;
+    util::dprint(errs);
     assert(stack_is_clear());
 }
 
@@ -976,8 +973,6 @@ void World::serialize(StreamBuffer *sb) {
         sb->write_int64(p.first);
         p.second->serialize(sb);
     }
-    // int64_t wc1 = sb->total_writes();
-    // std::cerr << "World serialized to " << wc1-wc0 << " bytes." << std::endl;
     assert(stack_is_clear());
 }