Remove budget priorities:

Remove budget priorities:
(budg, player_coms): Remove command arguments.
(PRI_SMAINT, PRI_PMAINT, PRI_LMAINT, PRI_SBUILD, PRI_PBUILD)
(PRI_LBUILD, PRI_MAX): Remove.
(natstr): Remove member nat_priorities.
(add, main): Remove its initialization.
(budg, cal_call, prexpense, prod, update_main, upd_land, upd_plane)
(upd_buildeff, produce_sect, upd_ship): Simplify.
(produce_sect): Last parameter now superflous, remove & simplify.
(change_prio, do_prod): Unused, remove.

(budg): Move land units output down, to match update sequence.