Add option to increase privacy lookup (zero knowledge option)

[cpina]

When a user uses Kamus and looks up for a word, the word is sent to the server (cyphered) and the server looks up the word in Wiktionary. The server knows which word, and can be found in the logs.

It is possible to increase privacy of the users implementing a "zero knowledge" from the server point of view. For example, sending a hash for the word if the hash matches a reasonable number of entries in the dictionary. The server would return quite a few entries and the browser should display only the required one. Needs consideration to avoid revealing the word using the autocomplete.

This can be useful for people that doesn't want to send the looked up word over the internet in case of rogue SSL certificates (man in the middle attacks) or that want to avoid even Kamus server and Wiktionary know which word they were interested in.