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-capture-pane.c

@@ -41,7 +41,6 @@ const struct cmd_entry cmd_capture_pane_entry = {
 	"[-aCeJpPq] " CMD_BUFFER_USAGE " [-E end-line] [-S start-line]"
 	CMD_TARGET_PANE_USAGE,
 	0,
-	NULL,
 	cmd_capture_pane_exec
 };