OPEN - task 4: Create initial TODO preference page entries 
https://github.com/joergreichert/XtextPlayground/issues/issue/4
OPEN - task 6: Set marker priority according to settings 
https://github.com/joergreichert/XtextPlayground/issues/issue/6
OPEN - task 10: Handle TODO containing comment at the end of file 
https://github.com/joergreichert/XtextPlayground/issues/issue/10
OPEN - task 5: Improve exception handling in XtextTaskCalculator.java 
https://github.com/joergreichert/XtextPlayground/issues/issue/5