While the previous function technically worked, the connections
weren't setup properly. Also the row_count function wasn't running
because it requires a QModelIndex parameter. Added a simple count
function to make sure we know how many slides there are in QML.
This model, built in Rust, works in that functions are getting called
and the right pieces are mapped into the model. I've yet to connect
things up to see if QML is talking to the model just yet.