Spline files cloud storage and URL publishing

This update introduces cloud storage for Spline files and a new URL publishing feature.

Changes

• Spline files are now stored in the cloud!
• Create, rename, edit, delete files in the cloud (warning: there is no trash can yet, so be careful about what you delete).
• New URL publishing feature. You can export your scene as a public URL.
• New Image exporting feature.
• New profile views for files!
• New tab system to handle your files.
• Double click on a tab to rename the file.
• File sizes are now smaller (from 2x to 50x in some cases).
• Fixed several stability bugs.