Feature Request: Mean shift clustering

[bdeonovic]

It would be great to have an implementation of an algorithm that finds modes of kernel density estimates. Most common algorithm is mean-shift algorithm:

Comaniciu, Dorin; Peter Meer (May 2002). "Mean Shift: A Robust Approach Toward Feature Space Analysis". IEEE Transactions on Pattern Analysis and Machine Intelligence (IEEE) 24 (5): 603–619. doi:10.1109/34.1000236.

A great short (2 page) guide to using mean shift algorithm for clustering http://homepages.inf.ed.ac.uk/rbf/CVonline/LOCAL_COPIES/TUZEL1/MeanShift.pdf

I initially posted the request at KernelDensity.jl (JuliaStats/KernelDensity.jl#11) but thought it might be better suited here.

I made a pull request: #43