This package uses a count-min sketch and a heap to track the top K items
in a stream of data. Tracking a new item and adding a count to an
existing item both require no memory allocations and is at worst
O(log(k)) complexity.
Change-Id: I0553381be3fef2470897e2bd806d43396f2dbb36
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>