Neo-tree v3.0 released

PSA - Neo-tree has just moved on to version 3.0!

In this project, a major version change is not about features, it's just about making breaking changes in a way that lets users opt into them when they have time.

v2.x will no longer be updated unless we find some kind of massive bug, such as if your computer catches fire when opening neo-tree. If you use a release branch (which you should) and you want to keep getting updates, you'll need to switch your branch from v2.x to v3.x.

Checkout the release on github for a list of changes in this release.