Corruption with addLine but not addRGB565Line

[prplz]

I was experiencing corruption of the png when using addLine, but not when using addRGB565Line. I noticed they don't share code and they aren't identical, and copying the "good" code from add565 fixed the issue for me even though I didn't look into what the actual changes are: bd26d99.

[bitbank2]

Thanks for finding this. I'm super busy on a bunch of other projects. Can you do a pull request?

[prplz]

Sure! Is it ok if I also make addRGB565Line tail call into addLine to deduplicate the code?

[bitbank2]

certainly - thanks :)