v0.4.0

PointNeighbors v0.4.0

Diff since v0.3.1

Merged pull requests:

• Improve docs for plot_benchmarks (#39) (@efaulhaber)
• Use contiguous backend for FullGridCellList (#40) (@efaulhaber)
• Add benchmark for update! (#41) (@efaulhaber)
• Implement fully parallel update with atomic operations (#42) (@efaulhaber)