Began fleshing out the ImtLinkSet class, after some trouble deciding whether to base it off QAbstractTableModel or QStandardItemModel, and whether to keep the links in a QMap or QHash (chose the former in both cases). It compiles, but doesn't have enough functionality for testing yet.

I'm still unsure about QMap; it may be that a simple QList with some lookup functions would be way better in the end.