Cargo dependency tree

Node?s npm has a nice feature: You can list all packages and their
dependencies. cargo has no such feature included, but cargo-tree
delivers. Install it with

    cargo install cargo-tree

and it gives you a nice tree of dependencies for all libraries in
Cargo.toml:

    $ cargo tree
    postgres v0.10.2 (file:///Volumes/git/rust/rust-postgres)
    ??? bufstream v0.1.1
    ??? byteorder v0.4.2
    ??? hex v0.1.0
    ??? log v0.3.4
    ?   ??? libc v0.2.4
    ??? net2 v0.2.20
    ?   ??? cfg-if v0.1.0
    ?   ??? kernel32-sys v0.2.1
    ?   ?   ??? winapi v0.2.5
    ?   ??? libc v0.2.4 (*)
    ?   ??? winapi v0.2.5 (*)
    ?   ??? ws2_32-sys v0.2.1
    ?       ??? winapi v0.2.5 (*)
    ??? phf v0.7.9
        ??? phf_shared v0.7.9