Feature Request - improve the image editor usage
I find the pixel editor mostly fine for my (limited) uses so far, but I think a couple of things could make it much better:

1. **Import and Export images**
Sometimes I want to export my work over to a different program. There doesn't seem to be a way to do that - the ctrl+c shortcut doesn't copy to the clipboard, only inside the program. There is no export option in-editor, and trying to look at the data inside reveals something that is not an image file (There's probably some way to convert that to an image file, but it would either require some coding or is not clear enough).
~~Also, maybe I should open a separate bug report, but dragging an image file into the editor doesn't seem to work for me. This means that the graphics is essentially secluded from other tools and resources - including even another pyxel resources file - which is inconvenient to say the least.~~

2. **Draw with the keyboard**
 Considering how most stuff in the Pyxel editor can be done using only the keyboard, it would be nice to have the option to draw using the keyboard as well. Some stuff in the image editor can already be done with a keyboard, like selecting a color, but it doesn't seem to have to option to actually draw using the keyboard.

3. **Changing the color palette should be clearer**
     - It took me a while of digging around in the README and FAQ to find how to create a palette file - it should be easier to find.
     - Having a way to change the palette inside Pyxel editor can be more convenient, although not necessary (I'd place it at a much lower priority over the other stuff I'd like to see implemented)