Import/Export drawings

[wazaraki]

It would be nice to be able to import and export pixelm drawings to a format like json.

Use cases for this would be:

• Saving changes to continue work later
• Savepoints, version control
• Saving and loading your own templates
• Sharing artwork
• Loading and viewing other people's artwork
• Maybe save user palettes (when supported) along with drawing?

[wazaraki]

Drawing data could be stored into the download file as metadata a la fireforks .PNG. Imports would be allowed for GIF/pixelm, SVG/pixelm, etc, "enriched" formats.

Not sure if this idea would simplify or complicate things though.