Fix rotation and voxel types

New features:

• config files are now optional thanks @markuspi
• new voxel type, improves readability and a bit performance @tizianoGuadagnino
• Rotations stays "roatations", the Python API still opeartes on 4x4 matrices @tizianoGuadagnino and @mattalvarado
• some typos fixed @LimHyungTae

Thanks everyone for the contributions!

kiss_sample.mp4