WIP: Feature/add countdown timer
Work-in-progress merge request
This adds a "Countdown Timer Plugin" to OpenLP.
Two operational modes are available:
- Countdown to specific time (i.e. 10:00 AM)
- Specific-duration countdown (i.e. 5 minutes)
I began this in 2014, but got completely sidetracked and forgot about it until now, so I'm trying to update the code to match the