freezeDeep method

[slegare]

It would be great to have access to a freezeDeep method that would recursively call Object.freeze() on an object.

There is a lib that does it which was last updated 13 years ago, and at version 0.0.1, but is still downloaded a lot: https://www.npmjs.com/package/deep-freeze. I believe it would be a good addition to deepdash.

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I created an issue as I thought it was the way to request for new features: #146. If you prefer to close it and reopen if the feature is to be implemented, please do so 🙂 If you want me to contribute, I would gladly work on it now as I might use it in the near future.