Updated Polish translation
Updated Czech translation
Use radio buttons in scan dialog

Convert check buttons in scan dialog to logical groups of radio buttons.
Remove redundant grouping of scanner radio buttons

As the scan dialog radio buttons are in built-in groups, there is no
need to add them to additional groups and manage the toggled state
inside EasyTAG.
Allow the scan files button to be made default
Visually group radio buttons in the scan dialog

Use a new GtkBox per group of radio buttons, and add spacing between the
groups so that it is more obvious to which group each option belongs.
Fix Roman numeral check button startup sensitivity

Rather than always setting the Roman numeral check button sensitive in
the scan dialog, do so only if the associated capitalizatin radio button
is active.
Updated Polish translation
Updated Spanish translation
Updated Czech translation
Avoid continual growth of TrackEntryComboModel
Refactor track number to string formatting

Add et_track_number_to_string() to consistently handle track number
formatting.
Add APE tag "part" constant
Updated Spanish translation