tribe_events shortcode support multiple categories with option for AND or OR
Per https://theeventscalendar.com/knowledgebase/embedding-calendar-views-tribe_events-shortcode/#common, only 1 category can be entered in the shortcode.
I'd like to be able to do something like this:
`[tribe_events categories="bbq,holidays,community" and="true"]`
(since the default would be `and=false` which means OR, not AND)
Another name for this shortcode argument might be `filter="and"` or something else.