section_id is messed up when listing items

[dwrdx]

If an item does not belong to any section, the section ID will be null, the previous change didn't take this into consideration, which would cause messing up of sections for items.

Changed the type of section_id from int to empty interface to fix this bug

[psethwick]

I think this must be fixed some other way, now.

I had the issue but I think it's actually caused by incorrect (old) data in cache.json. I deleted it and the master branch no longer exhibits the incorrect sections.