A simple plugin to prevent the old to "Missing Part-now a dozen vessels are deleted" thing from happening.
The plugin runs once when you first start KSP and load a game. It generates a backup file before any changes can be made to the persistent file, ensuring that no active flights will be lost if you delete some parts from your GameData folder, or otherwise corrupt your installation somehow.
A config file is included in the installation folder. Within the file you can specify how many backups you want the plugin to create before it overwrites the oldest backup again. The default is 3 backups. The config file must be placed in the correct location to function:
Kerbal Space Program/GameData/AutoSave/Settings.cfg
Source can be found on GitHub.
License is 2-Clause BSD.