Inclusion of Hclust into Clustering.jl

Hi, 

Following the suggestions from the METATDATA maintainers, I made a patch for Clustering to absorb the package Hclust (Hierarchical clustering along the lines of R's hclust() and cutree()), sice this is also does a form of clustering.  This keeps the number of packages down.  

I did not further integrate the code, it seems to be reasonably independent of the existing code in Clustering. 

---david


I see your point, and I can easily change these names, I'll add another commit shortly.  

But I think there are many functions that have quite a different meaning depending on their arguments (zip(), Array(), sum(), similar(), etc)---and that is not just the first argument as in traditional object oriented languages.  

I've always seen it as one of the cool things that I don't have to think of new function names all the time when I develop code in steps to operate on increasingly more complex objects, as in 
mycoolfunc(a::Array) = map(mycoolfunc, a)

And there are already a lot of functions defined in Base (max and maximum are already taken, so where do I go? I find "mymaximum" lacking any fantasy.)  I'll probably go for utmaximum().