xdump:
(gamestr): New member game_upd_disable.
(game_ca): Update accordingly.
(game_ctrl_update): New.
(disa, enab): Use it.
(updates_disabled): Rewrite and move to game.c
(disablefil): Remove.
synchronized to updates (the one based on s_p_etu isn't synchronized):
(gamestr): New members game_turn, game_tick, game_rt.
(game_ca): New selectors for them. Restrict tick and rt to deity for
now. We'd need xdump update the Empire clock to make them safe for
players.
(game_record_update): New.
(update_main): Call it.
(game_tick_tick, game_tick_to_now, game_step_a_tick): New, not yet
used.
