Created Explanation window
Choise of Categories implemented, difficulty security check inserted
Merged master and jesperSPQuizforstsat, including choice of categories
Merge branch 'master' into MarcMPQuiz

Conflicts:
	RedderAppAndroid/AndroidManifest.xml
	RedderAppAndroid/res/layout/activity_explanation.xml
	RedderAppAndroid/res/values/strings.xml
	RedderAppAndroid/src/com/redderappandroid/MainActivity.java
	RedderAppAndroid/src/com/redderappandroid/QuizWindow.java
	RedderAppAndroid/src/com/redderappandroid/ResultWindow.java