The second beta release of 3.1.1 is up, with a bunch of improvements and fixes over the last one. The enhanced music/audio playback stuff is back from older drd builds as well.
As per usual, check the GitHub release page
for more details on what has changed since beta 1.
The last thing I'm planning for 3.1.1 is undo/redo in the texture editor (which is mostly done), once that is in it'll just be a matter of more testing and bug fixes before 3.1.1 final is released, which should hopefully be early next year.