"Task Tags" detection should only generate Task markers

[nitind]

The current defaults allow for generating Problem markers. There are already 3 severities for the task markers, and creating markers under a different root marker type means they don't show in the Tasks View. This does not behave the same way as other language support within Eclipse, and I especially don't understand the rationale behind having "NOTE" in a comment result in a Problem marker--of any severity.