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-paste-buffer.c

@@ -38,7 +38,6 @@ const struct cmd_entry cmd_paste_buffer_entry = {
 	"db:prs:t:", 0, 0,
 	"[-dpr] [-s separator] " CMD_BUFFER_USAGE " " CMD_TARGET_PANE_USAGE,
 	0,
-	NULL,
 	cmd_paste_buffer_exec
 };