Acceptable image size and color profile description
**Is your feature request related to a problem? Please describe.** 
Yes - Photoshop PNG fails to load with `libpng` error shown below, and I can't afford Aseprite, so I want to convert the file to acceptable one but no such documentation exists for the format and the error handler just closes the entire editor.
![Image 285](https://user-images.githubusercontent.com/11834016/62002556-6eb72e00-b141-11e9-84a2-718478032f13.png)

**Describe the solution you'd like**
Add a line for the maximum acceptable size of the image in width and height, and acceptable color mode (RGB? Indexed? CMYK?) and export settings for Photoshop on the wiki alongside import guide.

**Describe alternatives you've considered**
File converter for the engine could be useful.

**Additional context**
This is the file I'm trying to import.
![Blackbeard_Logo_Pyxel](https://user-images.githubusercontent.com/11834016/62002568-b6d65080-b141-11e9-85a1-fc3f495aa33c.png)