Bugfixes for import, export and folder-tag linking

Improvements

• After importing a satchel, open it in a new tab and generate thumbnails

Fixes

• Fix files being added to wrong folder in a satchel
• Fix files in a satchel not being copied correctly on import
• Fix filepaths in satchel not being compatible between windows and linux
• Block importing or creating a collection with a name that is already taken
• Fix Folder-Tag links not working