Feature/write mesh fixes

[jefferis]

No description provided.

[codecov]

Codecov Report

Merging #514 (64fa2d0) into master (1d161fa) will decrease coverage by 0.02%.
The diff coverage is 60.00%.

❗ Current head 64fa2d0 differs from pull request most recent head 0660ee9. Consider uploading reports for the commit 0660ee9 to get more accurate results

@@            Coverage Diff             @@
##           master     #514      +/-   ##
==========================================
- Coverage   76.89%   76.88%   -0.02%     
==========================================
  Files          48       48              
  Lines        5926     5935       +9     
==========================================
+ Hits         4557     4563       +6     
- Misses       1369     1372       +3     

Files	Coverage Δ
R/neuron-io.R	84.87% <100.00%> (+0.15%)	⬆️
R/neuron-mesh.R	69.44% <33.33%> (-4.75%)	⬇️

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