Added:
- AMScanTableView ~ Class showing scan data in table form now lives in a
separate class outside of AMScanDataView
- AMScanThumbnailView ~ Class showing scan data in thumbnail form. Just
set up stubs for now to implement interface required by
QAbstractItemView

Altered:
- AMLightweightScanInfoFilterProxyModel and AMLightweightScanInfoModel ~
Now contains methods thumbnailCount and thumbnailAt to retrieve
thumbnails from the scan info collection