Use fclone to do serialization and prevent circular references

[piranna]

Using solution at #4 found the problem of Error objects name and stack fields (and for native errors message fields too) were not being included because they are non-enumerable, leading to native errors with an empty objects. Due to this, I've taken the path to prevent circular references and decided to use the https://www.npmjs.com/package/fclone module, since doesn't have any dependency and seems to have a good usage popularity. I can confirm that this works as expected, showing the missing fields in Error objects (code has an explicit check for them), and circular object references are replaced by a [Circular] string.

I've done this in a new pull-request since previous one is hosted on my company Github organization and I don't have write access to it anymore.