[MonoDevelop] Tab replacement for files proposal

[Levi Bard]

> The proposal is to create one tab for the file editor dialog and then
> polish and enhance the new navigation breadcrumb control.  We enhance the
> control by showing the currently opened file and then have functionality
> to be a drop down for picking another opened file.

I really like being able to manage my workspace of what files are
open, and see (a large number of) them at a glance.
I do think that the experience of discovering and browsing to
not-currently-visible tabs could use some improvement (there have been
some suggestions on that - one was an eclipse-style dropdown at the
end of the tab bar), but I really REALLY dislike the xcode experience
of always having to pick the active file from the dropdown, not being
able to easily manage my working set of files, not being able to see
the open files at a glance nor quickly switch between them, etc.