SplitBodyCarving: Switch current raveler label when navigating to an annotation.
Carving: Comment.
fixup! SplitBodyCarving: Switch current raveler label when navigating to an annotation.
OpSplitBodyCarving: List fragment names in sorted order, and pair each fragment with the correct label value.
SplitBodyCarving: Override _update_rendering() from Carving base class so that only (masked) fragments and the current segmentation are shown.
Carving: Allow calls to deleteObject for object names that don't exist.
SplitBodyCarving: When a new fragment is created, don't save&load an empty object.  Treat the "current fragment" as a "saved fragment" for the purposes of display in the table, though.
LabelListModel: Avoid an occasionaly IndexError during first selection.
SplitBodyCarving: Don't enable context menu or 'browse' button.
SplitBodyCarving: Don't bother clearing the seeds when a new fragment is created.  (There shouldn't be any seeds present.)
SplitBodyCarving: Make sure the user can't select the label list when a fragment isn't active.
SplitBodyCarving: Auto-select and navigate on double-click in body list.
OpSplitBodyCarving: Fixed an IndexError.