Cyclic

**New datatype** 
Von Mises with unknown mean and known concentration (there is no closed-form conjugate prior for concentration).

**Notes**: 
- Data is assumed to be in a 2π range from 0 to 2π. 
- This data type tends to be slower than the others because it tends to use a large number of clusters to compensate for having constant concentration across clusters (think kernel density estimation). In practice, this does not affect its joining appropriate views.