Long messages aren't being saved, and multiple keys

[rmasoni]

We currently have at least a client-side limit, set by HTML's maxlength, of 16384 characters. However, when you try to save a message this big, no UUID is generated — the link only contains the key, eg. vua.sh/#KEY.

Also, I just ran into another bug while testing this. When you generate a link, go back with the browser's Back button, type in more characters and create another message, the link also has no UUID and concatenates several keys, eg. vua.sh/#KEY1#KEY2#KEY3.