The undo stack needs to store regions [$15]

[erbridge]

Migrated from limetext/lime#211.

A view's associated regions need to be saved away in the undo-stack (or in edit objects perhaps).

For example, if I first load a file, then add a couple of regions, then delete the contents of the file. All regions will now have collapsed and merged into a single Region{0,0}, which is expected behavior.

Then I hit undo. I would now expect the regions to be what they were before I deleted the buffer contents, however what they will be instead is a single region covering the whole buffer.

--- There is a **[$15 open bounty](https://www.bountysource.com/issues/33624290-the-undo-stack-needs-to-store-regions?utm_campaign=plugin&utm_content=tracker%2F15716642&utm_medium=issues&utm_source=github)** on this issue. Add to the bounty at [Bountysource](https://www.bountysource.com/?utm_campaign=plugin&utm_content=tracker%2F15716642&utm_medium=issues&utm_source=github).

[AJ0070]

@erbridge is this still active?

[Shlummie]

Opened PR #131 to preserve view regions across undo/redo and added a regression test.