Dedicated link creation dialog

[kirillt]

We don't really need input fields when we are browsing through list of existing links, so better to hide them and invoke dedicated dialog by clicking a button. The dialog should also be interactive: just 1 input for URL and a button like "paste from buffer". When this input is filled, save button, as well as title and description fields must appear. New inputs must already contain filled-in text (similar to what is done by "autofill" button at the moment). "Autofill" button should be removed. The user can alter contents of title and description inputs before saving.