Add options for project which wish to make modifications to deps and use the mods when building.

[DiamondLovesYou]

Useful in case one needs to make a modification to a dependencies source, and would like to subsequently use the edited checkout instead of a cargo managed checkout.

Ie:

# --umbrella puts the repo in one level higher than highest level cargo project
# ie if your project was at /foo/bar/far, where 'far' is a nested crate inside bar, 
# cargo clean should checkout the project to /foo/project-name.
#
# --override-dep adds a cargo config path entry for the project;
# using the previous example, the config file is placed so it overrides 'bar' 's deps when 
# --umbrella is given, else the project present in the current dir.
cargo clone --umbrella --override-dep

[JanLikar]

Thank you for reporting the issue. I'm currently not doing a lot of open source development, so this might take a while.

[JanLikar]

Implementing "editable checkouts" does require cloning, but I think its purpose is orthogonal to the purpose of cargo-clone. I think this should be a separate subcommand, possibly having cargo-clone as its dependency.