Remove old_t_* enumerations.

Remove map::oldter, reverse_legacy_ter_id. use map::ter and current t_* values instead.
Rewrite the switches into if-else-if structures.
Apply astyle to map::hit_with_acid

Fix bug in iuse::hacksaw: don't check the terrain type != 0 (=t_null), it's always non-null.
Remove old_f_* enumerations

Remove map::oldfurn, nearly nowhere used.