v0.32.18

VortexPasta v0.32.18

Diff since v0.32.17

Merged pull requests:

• Show movie/gif of turbulence simulation in docs and README (#92) (@jipolanco)
• Implement HostVector for more robust CPU <-> GPU data transfers (#93) (@jipolanco)
• Parallelise some CPU -> CPU copies (#94) (@jipolanco)