v0.2.1

• Chain a rustc wrapper set in Cargo configuration, such as a global sccache in ~/.cargo/config.toml, when salting layout replicas, instead of refusing to prepare them. The wrapper is found as Cargo finds it: the environment, then build.rustc-wrapper in the configuration nearest the tree, then $CARGO_HOME's, including files they include, with relative paths resolved as Cargo resolves them. An empty $CARGO_HOME counts as unset, and a relative one is relative to the tree, as for Cargo. Invalid configuration files are reported with their parse location.