I finished the code for the 'NeoPixel Painter' Library and it is available now from the library manager. I already posted this in the official Arduino forum but I actually developed the library on an ESP8266.
In a nutshell it makes it very easy to do animations with fading effects on LED pixel strips. It is using the Adafruit NeoPixel library and adds some functionality for color animations.
See the Video of the example animations I wrote to demonstrate what the library can do (sorry for the bad quality, shot it using my phone).
Visit the Git repository for details on how to use it or check the examples.