RelativeDate: introduce delta and deltaSteps accessors
switch to deltaSteps where appropriate
fix deltaYearSteps to take into account leap years
fixup: typo in getDateString
pull in getWebContentHandlerByURI through the correct interface
Merge pull request #73 from tanriol/fix-get-handler

pull in getWebContentHandlerByURI through the correct interface
Merge pull request #44 from tanriol/time-intervals

Use more correct display for time intervals