SEATT updated to 1.5.1

Simple Event Attendance has been updated to 1.5.1.

This is to fix an issue with PHP7.2 where debug logs contain a count function warning:

Warning: count(): Parameter must be an array or an object that implements Countable in /var/www/html/wp-content/plugins/simple-event-attendance/seatt_events_include.php on line 103

The few lines where this was a problem were updated to check if the variable was empty. See changelog on the PHP count function spec.

Plugin is live on wordpress.org, and available on GitHub.