Computation times

00:01.991 total execution time for 4 files from gallery/spines:

Example	Time	Mem (MB)
Spines (spines.py)	00:00.668	0.0
Spine placement (spine_placement_demo.py)	00:00.565	0.0
Dropped spines (spines_dropped.py)	00:00.422	0.0
Centered spines with arrows (centered_spines_with_arrows.py)	00:00.337	0.0