[Code Cleanup/SDK] Removed another deprecated SDK example (mail tabs).
[Code Cleanup] Removed some deprecated ACL privs and strings
6.0 version checkpoint
[Code Cleanup] Plugin manifest tweaks for 6.0
* [Pages/Workspaces/Plugins] Implemented a new extension point (cerberusweb.ui.workspace.tab) for creating workspace tabs with completely custom functionality.  Rather than just containing a set of worklists, a tab extension could display a dashboard of reporting metrics, etc.  This extension point is currently used to provide a 'Knowledgebase Browser' tab that can added to any page.
[Code Cleanup] Fixed an issue with the upgrade patch from 5.8 to 6.0
[Code Cleanup/Pages/Tabs] Tweaked the code for adding a new workspace tab so it always shows the 'Type' option.
[Code Cleanup/Menu/Usability] A worker can now click anywhere in the global navigation menu, rather than exactly on a link.  This requires less mouse finesse and reduces strain.
[Code Cleanup/Usability] The 'transfer' effect is now more pronounced when adding or removing pages on the menu.  The previous 'dotted outline' was only visible with highly contrasted and calibrated displays.  A filled box is now used as well to make this more obvious.
[Code Cleanup/Usability] 'Add Tab' will now re-focus the 'Title:' field after adding a tab.  This makes it easier to add several tabs at once.
* [Pages/Worklists/Usability/Performance] The parameters of new worklists will now start with contextual defaults when they are added to a workspace tab.  Previously, a worklist of tickets would start with no parameters, which could lead to it trying to display the first page of millions of rows.  Now ticket's will default to open/waiting, tasks to 'not closed', etc.

[Code Cleanup] Moved workspaces-related actions from the Internal controller to Pages.
* [Worklists/Mail/Usability] The 'In Groups of Worker' filter on mail worklists can now use the 'Current Worker' placeholder.  This allows you to make a shared worklist that is dynamically constrained by the group memberships of the worker looking at it.
6.0-dev Checkpoint
[Code Cleanup/Consistency] Updated all the uses of the icons for plus-circle, minus-circle, tick-circle, and cross-circle.  The -frame versions have been removed since the interface looks smoother when it has fewer borders.
[Code Cleanup/Knowledgebase] Finished implementing the KB browser as a workspace tab.  Fixed an issue with Topic subtotals on KB article worklists.  Implemented the 'pretty delete' process when editing categories.  Combined code for managing topics and categories.
* [SDK/Pages/Workspaces] Added an SDK example plugin (example.workspace.tab) for demonstrating how to make new workspace tab types.
[Code Cleanup] Condensed more code for Pages; fixed a null reference issue
* [Pages/Workspaces] Implemented a new extension point (cerberusweb.ui.workspace.page) for creating custom page types.  A custom page can display any kind of content, and otherwise such pages are seamlessly integrated with workspace-based pages.  For example, the reports plugin now implements a custom workspace page to display reports -- which is useful, since the format of reports is outside the typical "workspace of worklists" pattern.
* [SDK/Plugins/Pages] Added a new SDK example for implementing custom workspace pages using the 'cerberusweb.ui.workspace.page' extension point.
* [Worklists/Messages] Added a 'ticket is deleted' filter to message worklists.