Feature Request: fuzzy string matching to match domain to entry name if no matching URL found

[thiswillbeyourgithub]

Steps to reproduce

1. Use password manager for years, with another client, and never set the url for an entry
2. Make the switch to passman and be happy
3. Notice that it would really be helpful to use fuzzy string matching to find the best match between the current web page domain and the name of the entries that don't have an url specified

Expected behaviour

If no entry have the corresponding URL set BUT the user still clicked on the passman icon, that plausibly means that the passwords are saved in an entry that does not have URL specified, so fuzzy string matching could be used to suggest the best match

Actual behaviour

When you click on passman and no URL for the page is set, you have to manually search for the right entry, select the username, copy and paste it, then redo that step for the password (because of #349)

Configuration

Browser: Firefox

Extension version: 2.1.1