Instead of setting up the default keys by building the key struct

directly with a helper function in the cmd_entry, include a table of
bind-key commands and pass them through the command parser and a
temporary cmd_q.

As well as being smaller, this will allow default bindings to be command
sequences which will probably be needed soon.

cmd-display-message.c

@@ -35,7 +35,6 @@ const struct cmd_entry cmd_display_message_entry = {
 	"[-p] [-c target-client] [-F format] " CMD_TARGET_PANE_USAGE
 	" [message]",
 	0,
-	NULL,
 	cmd_display_message_exec
 };