ISIS-537: removing a TODO:mgrigorov (comments only)
ISIS-537: moved markup and CSS for LinksSelectorPanelAbstract into its subclasses (CollectionContentsLinkSelectorPanel and EntityLinksSelectorPanel).
ISIS-537: moved impl of LinksSelectorPanelAbstract (.java) to subclasses.
ISIS-537: deleting LinksSelectorPanelAbstract, no longer used.
ISIS-537: render selector panel-specific CSS to ensure that unselected views are not shown.
ISIS-537: updating comments only.
ISIS-537: collection actions now rendered in the panel header.
ISIS-537: factored out CollectionContentsSelectorDropdownPanel from CollectionContentsLinksSelectorPanel.
ISIS-537: refactoring out SelectorHelper
ISIS-537: completed factoring out of CollectionContentsSelectorHelper.
ISIS-537: mostly refactored, however hints not honoured for LinkSelectorPanel.
ISIS-537: selector drop-down now moved to EntityCollectionsPanel (ie into the panel header).
ISIS-943: Make ObjectContracts more resilient
ISIS-942: Allow auditing in transactions of entities being created/deleted.
ISIS-537: tidy up of (entity) collections panel; standalone collections panel no longer failing (but still need to sort out CSS and bulk actions)
ISIS-537: starting work on moving bulk actions up to panel header (renders but looks nasty and the selector does nothing).