New journal event command

Redundant information, but makes the journal easier to read.  The
redundancy might help making a journal replay tool robust.

Put it in Hvy Metal II now to gather some real data.

src/lib/subs/journal.c

@@ -44,6 +44,7 @@
  *     prng NAME SEED
  *     login CNUM HOSTADDR USER
  *     logout CNUM
+ *     command NAME
  *     input INPUT
  *     update ETU
  */
@@ -173,6 +174,13 @@ journal_input(char *input)
     journal_entry("input %s", input);
 }
 
+void
+journal_command(char *cmd)
+{
+    char *eptr = strchr(cmd, ' ');
+    journal_entry("command %.*s", eptr ? (int)(eptr - cmd) : -1, cmd);
+}
+
 void
 journal_update(int etu)
 {