InputEditor for rates and rateChangeTimes

[gavryushkina]

A BEAUti input editor that will handle multidimensional entries for rateChangeTimes parameters is needed. Also it would be good if this editor takes care of keeping the dimensions for the rate and respective rateChangeTimes parameters the same.

[gavryushkina]

One solution is to create an Input editor that derives from ParameterInputEditor and also create a special ChangeTimesParameter that derives from RealParameter. This solution is simple although the old xmls file will be not running as the type of birthRateChangeTime input (and others) changes from RealParameter to ChangeTimesParameter