Adds tooltips for saved tabs, other minor changes

Entries in the Saved Tabs gallery on the Home tab now have a tooltip
showing the tabs in that list (note: does not use "friendly" paths).
Localizes menu items on View tab (Ascending, Descending, More Columns),
changes to manual RTL override, removing the need for an extra registry
key. (Note that for certain installations, RTL may be manually set to
False from now on; to turn off manual override, set the RTLMode registry
key to notset ). Re-enables error handling for a rare NullException
occurrence.