build_index_cpp now sorts the data and structure the information with 'group_sizes' and 'biggest_group_size' attributes. #56
replace Index_0_based by SlicingIndex that takes advantage of the imposed ordering of the data. #56
initial internal impl for right_join. #96
using boost::scoped_ptr to rm the explicit delete call.
sketch the support class ShrinkableVector
sketch the support class ShrinkableVector
expose max_group_size as a method of GroupedDataFrame
Merge branch 'sorted'