HiC.scala
    Implemented addInteraction() method for class InteractionGraph.
    Currently the graph is implemented as a Vector where each element of
    the Vector is a HashMap[Interaction, Interaction].  The same
    interaction is used as the key and the value.  This enables looking
    up an interaction and updating the number of reads in the
    interaction.  I could not figure out how to do that with a HashSet.
    The HashMap is immutable.

modified:   .gitignore
deleted:    lib/algs4.jar
deleted:    lib/sam-1.113.jar
deleted:    lib/stdlib.jar
    Do not need these right now.  Also, algs4.jar imports
    java.util.Vector which gets in the way of scala's Vector (annoying).