New Im- and Export functions for 3DSlicer in Morpho

Hi everyone, those of you working with 3DSlicer may have seen that as of version 4.11, Slicer introduced a new json-based markup format. It now supports Curves (open and closed - pretty cool!) as well as traditional markups. Last week I added two new functions to Morpho: read.slicerjson and write.slicerjson that allow im- and exporting to the new format. As Slicer also changed the internal coordinate system to LPS, I also added the function LPS2RAS that converts both ways (as the transform is self-inverse).

How to install the latest development version

devtools::install_github("zarquon42b/Morpho")

Please test it and report back issues or missing functionality.