Make message copyable

Modal windows does not allow for data copying.
It is avoided by not using "alert", but making it into additional element in see.php.
ex. make function "decryptAndDisplay" like so:
```
function decryptAndDisplay(){
key = document.getElementById("client_key").value;
document.getElementById("message").style.display = 'block';
document.getElementById("found").style.display = 'none';
show_message = document.getElementById("message");
show_message.innerHTML = XORCipher.decode(key, enc_msg);
key = null;
enc_msg = null;
```
and add this somewhere inside of in see.php
```