Renames intervalsEndingInNode to IntervalsEndingInNode
Keeps track of IntervalsEndingInNode incrementation and decrementation by returning a reference to the endpoint nodes, so intervalWasAdded/Removed reflects both endpoints. This allows us to keep track of intervals ending in a node that they should not be stored in.
Prints graph for small IBS test
Merge branch 'master' of https://github.com/lundmikkel/C5