xterm-keys has been on by default for 5 years and all other modern terminals

use these key sequences by default. Merge the code into the main tty and input
tree processing (convering the latter to use a tree rather than a table at the
same time) and make the option a no-op.

server.c

@@ -198,6 +198,7 @@ server_start(struct tmuxproc *client, int flags, struct event_base *base,
 	    "tty ps", NULL) != 0)
 		fatal("pledge failed");
 
+	input_key_build();
 	RB_INIT(&windows);
 	RB_INIT(&all_window_panes);
 	TAILQ_INIT(&clients);