The files in Tooll2_upgrade_20190116.zip upgrade the 0.3.1 release of Tooll² to the current Git version including the new "custom loader" feature, along with the required changes in Operators.
To use this, simply copy the files from this archive into your Tooll² working directory, overwriting files that are already there.
After that, delete your Temp directory, otherwise some operators (e.g. Bend) won't work.
Why would I need that?
Not much has changed in the editor itself, except for a few bugfixes; however, the player has got a significant overhaul, with a possibility to show a custom operator instead of the classic loading bar, a more modern UI, a pre-caching option to reduce scene change jerkiness, command-line options, and delayed exit (the player exits 2 seconds after the demo's end, not immediately).
Is it production-ready?
There are some minor issues with custom loader screens (see the CustomLoaderHOWTO.md file for details), but it sure is stable enough for the bigscreen. It has been used for the Revision 2019 Invitation, for example.