Migrate to SLNX

[Lamparter]

SLNX (new XML-based Visual Studio solution format) is extensible and easier to edit than IronPython's growing solution file.
It would be a good idea to migrate to it.

[slozier]

In theory I don't have an objection (it's indeed nicer). However, I would wait until the feature is no longer in preview. With the latest VS release (17.13.5) the feature is hidden behind a preview flag which is a bit of a barrier to entry. Currently, the main purpose of the solution file is to be opened in Visual Studio, so it has to work out-of-the-box.

[Lamparter]

Yep, good idea