1.9.10.8: Grab Bag of Fixes and Features

This release is mostly focused on improving Kotlin support and third-party extensions. It also updates Gradle to 6.4.1, Groovy to 3.0.+, and Scala to 2.13.+, and there's some hopefully-usable work on the Android target. The third-party extensions added are MrStahlfelge's ControllerUtils (to handle controllers sanely, plus a scene2d option for the library when no controller is connected), crashinvaders' gdx-vfx (for nice and easy post-processing effects, including a predefined set of them as an extra dep), and tommyettinger's anim8 (for writing animated gif and png files from Pixmaps). This release also fixes the version check, and should pop up a toast if a newer version has been released and you're using this version. 1.9.10.2 to 1.9.10.7 had the version check disabled because I forgot about it. Whoops.

Thanks to QuillRaven for bug-finding several problems with Kotlin integration and/or Android stuff, and the libGDX Discord for actively testing 1.9.10.7 almost as soon as it came out. If you encounter any problems or just have requests for third-party libraries, feel free to post them as issues.