Allows a WordPress site to act as a MailChimp webhook.
Plugin will toggle a new user meta variable, _newsletter_subscriber, when a user subscribes or unsubscribes from a MailChimp list or will, optionally, add new subscribers and delete unsubscribers.
The URL listed in the plugin's settings page needs to be used when configuring the webhook in MailChimp.
Create a config.php which includes the defination of
MCWH_LIST_IDS
which is a map from mailchimp list id to user_meta_data prefix,
and
COMMON_TAGS
which is a map from mailchimp field to user_meta_data field name.