Merge pull request #3 from rithram/master

BBtree construction and related changes
Wrote basic LeftNN search

Also, extended KL Divergence to handle zeros somewhat gracefully and
wrote tests for this
Wrote skeleton of MST construction
Working on overlapping lines approach to dual tree pruning proof
Started adding both centroids to bregman balls, currently broken
Added a main file which reads in options from the command line.

Plus some more changes to the code to comply with the changes
made to the BregmanBall class (keeping around both left and right
centroids and radii).

The given main file also tests the correctness of the left NN
search for a given data set and a test real data set is also
added.