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-detach-client.c

@@ -33,7 +33,6 @@ const struct cmd_entry cmd_detach_client_entry = {
 	"as:t:P", 0, 0,
 	"[-P] [-a] [-s target-session] " CMD_TARGET_CLIENT_USAGE,
 	CMD_READONLY,
-	NULL,
 	cmd_detach_client_exec
 };