+ Broken also in d185889f4, with init system revamp.
+
+JH/17 Bug 2113: Fix conversation closedown with the Avast malware scanner.
+ Previously we abruptly closed the connection after reading a malware-
+ found indication; now we go on to read the "scan ok" response line,
+ and send a quit.
+
+JH/18 Convert macro handling to be tree-based, from the previous linear list.
+ With the number of builtin macros we now have this is worthwhile,
+ dropping the config-file read time (during which new macros are checked
+ and registered, and macros are expanded) from about 500 usec to about 180.