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-choose-buffer.c

@@ -34,7 +34,6 @@ const struct cmd_entry cmd_choose_buffer_entry = {
 	"F:t:", 0, 1,
 	CMD_TARGET_WINDOW_USAGE " [-F format] [template]",
 	0,
-	NULL,
 	cmd_choose_buffer_exec
 };