Adding support for shortcode 'wpsp64in'.
Updating submodule 'SP64in' to point to the latest 'master' that supports session initialization.
Calling 'sp64inInit()' in the 'init' action handler.
Added the ability to configure the email link caption text.
Keeping the text domain name in a private member field.
Calling '__(...)' rather than '_e(...)'.
Added new configuration setting 'enclose_in_address_tag'.