Add the ability to constrain times to not overlap

add an event_id to the method so we can check against existing events

I ended up needing the flag/boolean for each calendar entity to check if datetime should be validated. this patch adds that change

a couple of mistakes in hook_update_N from 3 that are fixed here

Thanks for the patch, this has been merged into the 8.x-2.x branch: https://www.drupal.org/project/google_calendar_service/releases/8.x-2.x-dev →

Automatically closed - issue fixed for 2 weeks with no activity.