SpinDynamica 2.5.5 has been released here:
https://www.dropbox.com/sh/xpsntplbtoblp3v/bFMhVBlwuDApart from miscellaneous debugging and speed enhancements, some reorganization has been implemented. SpinDynamica may now be loaded by
Needs["SpinDynamica`"]
This instruction now reads in the other packages. All users should upgrade to v2.5.5