Plugins for reveal.js 4.1.+

A plugin collection for reveal.js 4.1.+

Changes: Seminar-plugin now supports Wake Lock API to prevent mobile devices of particpants to fall asleep. Customcontrols-plugin now is collapsible for mobile devices in portrait orientation.

Breaking changes: In this release the customcontrols-plugin is completely rewritten and configuration has changed. Toggle buttons in chalkboard- and questions-plugin are now deprecated and customcontrols should be used instead.