Function to return the thumbnail directory would be useful

Submitted by com..@..il.com

Link to original bug (#634666)

Description

The GIMP stores thumbnails into the .thumbnails folder in the user's home %LocalAppData%\Microsoft\Windows\INetCache\thumbnails\ folder on Windows. This is not where applications should store files on Windows, and can get messy. Instead, applications on Windows should store data into the AppData folder provided. This prevents personal files from getting mixed with other data.

I ask that an #ifdef WIN32 is added and makes GIMP use the Appdata folder to save configuration and thumbnail files.

Version: git master