On server, channel dprint through the readline-device. Also some refactors and quality improvements.

luprex/cpp/drv/drvutil.hpp

@@ -19,6 +19,14 @@
 
 namespace drvutil {
 
+// Read/write the console.
+//
+// These only work when the program is being run from an actual
+// text-based console.  Otherwise, they may go to the bit-bucket.
+//
+std::u32string console_read();
+void console_write(const std::u32string &cps);
+
 // Read the lua source from disk into an ostringstream.
 //
 // To pass the lua source into the DLL, here is what you do: Construct an