Flow project's snapshots can be taken by Flow Designer's simple versioning system. In order to create a version of the current project click the button right next to project name.
When you press the versioning button a popup window will appear to create a new version.
By clicking the button named "Create Version" at the top right corner of the window, name and description of the version will be asked.
Any version can be opened by double clicking the requested version. Currently there is no branching capability is available. But in order to return to a previous version and continue from that version you just need to save the project after opening a previous version. A warning will be displayed that master version will be overwritten with this version.