Squashed commit of the following:

commit 76689c23011bf960f5ba3e199659e8180455466d
Author: Pine Wu <octref@gmail.com>
Date:   Fri Jan 24 10:19:44 2020 +0100

    Clarify API

commit 88d772d62da5d912b54285aa52dc6d6a108ca587
Author: Pine Wu <octref@gmail.com>
Date:   Fri Jan 24 10:17:28 2020 +0100

    Tooltip

commit 11ef8012ae3e560d6db6fff26ba3c258e7eae4a6
Author: Pine Wu <octref@gmail.com>
Date:   Thu Jan 23 16:50:28 2020 +0100

    Hover to show link color and use cmd/alt click

commit 38655a70b3eed56b99e8018fb5c79bd41b6c4f56
Author: Pine Wu <octref@gmail.com>
Date:   Thu Jan 23 15:21:13 2020 +0100

    Add hack to always render underline a bit below

commit 959f6b13bf81885cc370f6099e5123142089599e
Author: Pine Wu <octref@gmail.com>
Date:   Thu Jan 23 11:32:37 2020 +0100

    Fix compile error

commit b5c50e872935e74503451bd2801227f82b8410f4
Author: Pine Wu <octref@gmail.com>
Date:   Thu Jan 23 11:19:52 2020 +0100

    Bring code link everywhere for Diagnostics

commit f88cd4cc4e2064fd96853373e26c12670161bf60
Author: Pine Wu <octref@gmail.com>
Date:   Wed Jan 22 17:24:54 2020 +0100

    Add Diagnostic#code2 and render it in hover/inline/panel

commit 2a13e3e4f62fd3707f2c03c1e814a8fdc557c367
Author: Pine Wu <octref@gmail.com>
Date:   Wed Jan 22 13:49:42 2020 +0100

    WIP

Adds a backup method to the custom editor API proposal. This method allows custom editors to hook in to VS Code's hot exit behavior

If `backup` is not implemented, VS Code will assume that the custom editor cannot be hot exited.

When `backup` is implemented, VS Code will invoke the method after every edit (this is debounced). At this point, this extension should back up the current resource.  The result is a promise indicating if the backup was successful or not

VS Code will only hot exit if all backups were successful.

Fixes #84789

If the task is running but not visible, show it

Fixes #84794

Fixes #84795

This method is actually deleting the entire backup home
folder for the workspace and it is possible that this could
lead to race conditions when a backup is running at the same
time.

Fixes #89031

fixes #89149

Replace "open results in editor" viewlet action with "open new editor"

#87212