Allow passing custom node-dependency-tree options?

[rmunch]

I'm hoping to use the noTypeDefinitions option exposed by the node-dependency-tree package, but I don't think it's currently possible to pass custom options to node-dependency-tree. I'm happy to open a PR for this, though wanted to confirm interest and ask about what the option might look like.

Madge currently exposes a few individual options that get passed to node-dependency-tree, so it might be easiest to just make a new one for noTypeDefinitions. On the other hand, a more general solution might be to just expose a customDependencyTreeOptions option or similar.

Thanks!