Contact form: send automatic confirmation to sender

Something Modified can't do by default:
When a customer fills out your contact form, you get an email, but not the customer.
For some end users this is confusing and they think it didn't work.

With this change, your customer will also receive an e-mail that the contact was successful and that you will get back to them as soon as possible.
A nice side effect: you can immediately test whether the e-mail address you entered exists, because if it doesn't - you will get this confirmation back as undeliverable.
As of Modified Ecommerce 2.0.7.2

This module is update-proof.