Cannot correct invalid primary email addresses

[Mike Conley]

Steps to reproduce:

1) In Evolution, create a contact with an invalid primary email address - something without the @ symbol, for example.
2) Open Thunderbird's address book, find the newly created contact, and change the email address to something valid.

What happens:

Thunderbird complains that the email address is invalid.

What's expected:

Thunderbird should realize that we've corrected the invalid email address.

The problem is that the invalid email address has populated the hidden primary e-mail address field that TB normally uses, and is running it's built-in validation across it. The easy solution would be to clear this form field value when the EDS contact editor code inits. It'd be a good idea to go through the TB validation code to see what other fields we should do this to.