Refinements to FilteredCBL UI
Factored label display out into its own node
Minor refinements
Label display box styling
Labels can be selected via FilteredCBL
ObservableList setters no longer create new instances
FilterableCBLs now reflect checked state
Additional guards for setters so their fields can't be unintentionally cleared
Issue panels are manually refreshed when the dialog is closed
Code cleanup; fixed more data binding issues