Navis

_Date: 02/04/20_

Imnprovements
- `navis.Volume` is now sublcass of `trimesh.Trimesh`

_Date: 28/02/20_

Improvements
- improved `navis.stitch_neurons`: much faster now if you have iGraph

Fixes
- fixed errors when using multiprocessing (e.g. in `NeuronList.apply`)
- fixed bugs in `navis.downsample_neuron`

_Date: 24/02/20_

Fixes
- Fixed bugs in Blender interface introduced in 0.1.9

_Date: 24/02/20_

Fixes
- Removed hard-coded swapping and translation of axes in the Blender interface
- Fixed bugs in `navis.stitch_neurons`

_Date: 21/02/20_

Fixes
- Again lots of fixed bugs

_Date: 23/05/19_

Fixes
- Many small bugfixes