Added campaign data array to return array in mailchimp_get_lists_by_email() and refactored code to accomodate. Implemented in order to minimize API calls.
Added wrapper function mailchimp_get_campaigns_for_email to implemment cacheing around MCAPI::campaignsForEmail() in mailchimp.module. Also, minor naming consistency in mc_get_lists_by_email fixes cascading up to _activity functions.