v0.3.1

Peridynamics v0.3.1

Diff since v0.3.0

Merged pull requests:

• Fix VTK reading bug (#152) (@kaipartmann)
• Change multithreading backend to Base.Threads (#153) (@kaipartmann)

Closed issues:

• HPC suitability (#14)
• The VTK read function errors if nothing is exported (#151)