Incomplete, don't use this yet
Alternative to Cydia Eraser that is much easier to update. Downloads and mounts rootfilesystem DMG for your iOS version. Then moves files from mounted DMG to the main filesystem. Still to be added: automatically erase all content and settings. Should work from iOS 7.0+, probably even earlier than that once I finish. The downloader will only support 10.0.1 and later. If you're on 9.3.5 and older, you'll need to download and decrypt the rootfilesystem yourself unless you happen to be on a device I used for debugging (currently iPhone4,1 8.4.1 only).
How you can help
If you know how to erase all content and settings programatically, please submit a Pull Request.