Hide the API key to improve security and prevent copying.

[rahulmasal]

Sir,

once an API key has been copied, please hide it and prevent the user from copying it again for security purposes.

[pakjensen94]

A good way of doing this would be to have us set up a 4-digit PIN code for revealing the API. It can also be built on further by adding a self-destruction (API deleting itself) if the wrong PIN is entered too many times.