TimeToDie Changed - events are ignored, instead hp values are polled,
currently three different algorithms on calculating TimeToDie:
InitialMidpoints, LeastSquared, WeightedLeastSquares
with default to WeightedLeastSquares - can be changed by
setting 'jps.timeToDieFunction = "WeightedLeastSquares"'.
All algorithms based on TimeToDie Addon: http://www.curse.com/addons/wow/timetodie
Merge pull request #245 from kirk24788/master

TimeToDie Refactoring