V. 2.26 - Avoid clobbering other plugins' events,  'Flip' to 'Check answer/Flip back', 'Got it' and 'Need more practice' grayed/disabled until flip

git-svn-id: https://plugins.svn.wordpress.org/qwiz-online-quizzes-and-flashcards/trunk@1051000 b8457f37-d9ea-0310-8a92-e5e31aec5664