added corners breed to mark the region of interest.
Changed drag events so that only links associated with nodes are draggable.
Changed all instances of setXY to have the arguments in float values instead of patch values
changed height of box and shape of corners
updated drag events for corners and nodes. On drag for meanlines, corners and nodes,
the node positions match up with the edge of the box.
refactored adjustSlopeOLines function to use helper functions