Allow users to specificy from name and email address when sending Thank You letters

The "FROM" name/email address isn't configurable when sending Thank You letters by email. It'd be real nice if this was available. Feedback from clients indicate that a Thank-you email is not always (or ever) appropriate to be sent from the logged-in user, as that is often a lower-level staffer and not necessarily a person in the org from whom a donor might expect a thank you letter. It is also not always appropriate to send from the org's primary email address, something like info@org.org isn't all that personal. Some steps to observe where selecting a FROM email address isn't available:

1. Contributions - Find Contributions - Any criteria
2. Select contributions
3. From Actions menu, choose Thank-you letters/Print or email
4. Set Print and Email Options to "Send emails where possible"
5. Observe there is no option to change the FROM: email address
6. Actions for Email-Send now and Receipts-Print or Email both allow modification of FROM address