[CREATE] Resolution information in ORA

[Boudewijn Rempt]

Hi,

Jens Reuterberg (a Swedish illustrator) posted this bug for Krita: 
https://bugs.kde.org/show_bug.cgi?id=321106. He would like to roundtrip 
ppi information between krita, gimp and other apps that support ora.

The spec doesn't define that at the moment. I see two possibilities:

* use the resolution information in the embedded png files (I do that in 
Krita for now)
* extend the stack spec with resolution information, for example like:

<image w="300" h="177" xres="300" yres="300">

I don't care particularly about the tags used, or whether we have 
resolution separate for x and y, or not.

Option 2 has my preference...

Boud