nick black 37a4114f42
O(1) z-axis moves #623
Replace the singly-linked z-axis with a doubly-linked list,
and reimplement all z-axis moves as O(1) functions.
Eliminate ncplane_move_{above/below}_unsafe(), as there are no
longer unsafe moves.
2020-05-20 15:32:27 -04:00
..
2020-05-20 15:32:27 -04:00
2020-05-20 15:32:27 -04:00