Add “Show in Finder” context menu when no items are selected

When you control-click the empty part of the file browser and select “Show in Finder” a Finder window will open showing the currently selected folder.

You can go about this other ways, but I find that this feature complements the already existing "New Folder" menu item in the no-items-selected context menu of the file browser.

This patch is public domain.
Make OakPasteboardSelector accessible

Issues remaining:

* VoiceOver for some reason cannot track keyboard focus
  (i.e. moving down the list with just down arrow does not move
  VoiceOver cursor). User has to move the VO cursor instead using VO-down
  (and keyboard cursor follows in this case)
* the pasteboard window isn't focused automatically for VoiceOver, user
  has to switch manually to it using VO-F2-F2
Make OakTabBarView accessible
Optimize path::disambiguate

We now sort the reversed paths and do a linear sweep.
Don’t link to GitHub’s download section

This is an attempt of satisfying issue #677 — not entirely sure what was intended by opening that issue (given that nothing is presently broken and I surely will figure out another place to upload the builds once GitHub’s service is shut down completely).
Update dialog plugins

Fixes #584
Show in Finder works for multiple selected items
Add folder’s display name to menu items

This is only for the menu which shows when there is no selection.
Exclude gutter from accessibility

This was read as “empty scroll view” (using voice over), so better to skip it.
Checkin release notes
Allow excluding untitled documents from document::scanner_t

The problem with this feature is that it includes all untitled documents including e.g. the current bundle item being edited. For things like ⌘T we only want to show untitled documents from the current window.
A full match should rank highest
Add reworked file chooser

Presently the ‘@symbol’ syntax is not implemented.

I have removed the glob text field (so fixes #601), if it comes back, it’ll likely be as a different control, but I think we can do without this extra filtering. You can set the various include/exclude patterns for the file browser.

The tabs are also gone, though you can still use Go → Go to Tab → [ Project Folder (⌘1) | Go → Open Documents (⌘2) ] and the “Open Documents” mode list all open documents from the current project window (so partial fix for #139).

It no longer waits for all items to be loaded when you hit return (fixes #672), though as all open documents from current window are preloaded, it shouldn’t cause a problem when pressing ⌘T + ↩ quickly to go to previous file.
Switch to reworked file chooser
Allow slashes in path string on find clipboard (⌘T)
Switch to generated properties
Fix typo in enum value
Improve code for showing VO tab menu

We now use standard API for showing the menu and position it relative to the VO-selected tab.
Make OFBPathInfoCell a public class

This is temporary — if it should remain public, we should rename it and move it to the OakAppKit framework.
Let file chooser show icon and close button

The close button is currently not working.