Setting required merge fields as required on the settings form. Addresses #1134964 and forward port of #949932.

Complete refactoring of the merge system taking advantage of tokens being in core. Removed both merge hooks as they would be redundant. To add additional merge values, simply use the token hooks and add values to the user collection. Resolves #1132674.

Refactored how newsletter was processing when creating new user accounts by moving code into hook_user_insert and not triggering mailchimp_subscribe_auth_form_submit(). Some additional cleanup as well.

remove while db_object loops left over from D6 port and change profile_categories() to profile_user_categories()

applying mailchimp.module.patch from #878520 and some additional auth form bug fixes and refactoring

greatly improved handling of anonymous sign up forms. If more than, presented in a combined form. Still available individually in blocks. Also resolves #810616.

Add proper individual block forms for authenticated users, plus a bunch of other refactoring. Addresses #829768.