Bug: SS changes e-mail content-type from plain to html

General problem:
Simply Static seems to change the default content-type of e-mails.

Example:
The password-lost e-mails can’t be read by the receipient, because an url such as
<https://example.org/wp-login.php?action=rp&key=ABCDEFGHIJKLMNOPQRS&login=admin>
will be translated to
<https: example.orgwp-login.php?action="rp&key=ABCDEFGHIJKLMNOPQRS&login=admin">
which will be invisible, when the e-mail is displayed. (Tested in thunderbird and outlook.)

Reason:
line 100 of /wp-content/plugins/simply-static/includes/class-ss-plugin.php says:
add_filter( 'wp_mail_content_type', array( self::$instance, 'filter_wp_mail_content_type' ) );
line 617 ff. are:

	/**
	 * Set wp_mail to send out html emails
	 * @return string
	 */
	function filter_wp_mail_content_type() {
	    return 'text/plain';
	}

Solution:
get rid of filter_wp_mail_content_type() and the whole filter in line 100.