Store PC reduction information

[Aaron3154518]

When we have S1->D->S2 and we remove S1, D as part of reducePCRelations(), we would like to store S1's information in S2. S2's node will have a line that says "Eaten: S1".
For something like S1->D1->S2->D2->S3, when S1,D1 are removed S2 says "Eaten: S1". When S2, D2 are removed, S3 says "Eaten: S2, S1".