- Added side pane for product preview and information
- Product selection is done with a separate pushbutton, so that user gets a
chance to preview the complete product information before committing to the
selection
- Supports two view modes: Grid View and List View
- View mode is automatically stored in Settings, so it will default to the
user's prefered mode
- Should address most concerns in #109 and #142
Note: must currently use QGuiApplication instead of QCoreApplication to
support QFont. Unfortunately, this means that glabels-batch must run
within a windowing system. Ideally, it would not have this requirement.