More mesh formats, Brainvoyager support, transforms

Version 0.1.12

• add support for reading meshes in GEO format
• add support for reading meshes in TRI format (also known as ICO mesh format)
• add support for reading meshes in OFF format, the Object File Format
• add support for reading meshes in OBJ format, the Wavefront object format
• add support for writing FreeSurfer patch files in the ASCII format version
• add support for reading and writing meshes in Brainvoyager SRF format
• add support for reading and writing morphometry data maps in Brainvoyager SMP format
• add many unit tests and test files, use covr
• deprecate (imo) useless parameter 'empty_label_name' to read.fs.annot. using it will show a deprecation notice. (Please open issue if you feel you need it.)
• add experimental support for CIFTI v2 morphometry data files (.dscalar.nii), based on the 'cifti' package by J. Muschelli
• add support for reading transformation matrices from files in LTA and register.dat formats