Add "Protect your privacy" page

[saivann]

This pull request can be previewed live here:
(merged)

This page gives more explanation about the limits of Bitcoin privacy, many concrete ways to increase privacy and also mention potential future improvements related to privacy (payment messages API, implicit mention of CoinJoin, potential GUI improvements, zerocoin, manual input address selection. etc.)

[gladoscc]

Looks nice however zerocoin may never be integrated with Bitcoin as the processing overhead is far too high. It's more of it's own alt coin.

[saivann]

Makes sense, I just tried to make it more obvious that zerocoin is far from a working (and reliable) feature, and just research and development.

[saivann]

I plan to merge this branch tomorrow. More proofreading / reviews are welcome. If someone would like to ask for a bit more time to review, please leave a comment.

[saivann]

The "Protect your privacy" page has just been published. If you see anything else that needs to be discussed or fixed, please open an issue or pull request.