Tree View Bleeding package

NOTE: This replaces the built-in tree-view package. The built-in tree-view package needs to be manually disabled.

Bleeding edge version of core tree view that includes pull requests 582, 549, 525, 469, 413, and source map support.

TODO: include 532

Explore and open files in the current project.

Press ctrl-\ or cmd-\ to open/close the Tree view and alt-\ or ctrl-0 to focus it.

When the Tree view has focus you can press a, shift-a, m, or delete to add, move or delete files and folders.