- [ ] Implement globbing on outputs.
- [ ] Add support for disabling cache via environment variable => extend Manifest
- [ ] Add support for remote caches (at least for write access).  => extend Manifest with
        ```rust
        /// Host name for write access to the cache directory.
        pub cache_host: Option<String>,
        /// User name for write access to the cache directory.
        pub cache_user: Option<String>,
        ```
- [ ] Check if ancestry and diffing work properly with merges (safe case: fail).
- [ ] Implement tests for Git and Cache modules.
- [ ] Extend documentation.
