added option $.whenOnScreen.recalcOnResize == true
add .$elm property to sizes object available to range functions - and to the event object for when(on|off)screen
reformatted the documentation
`recalcOnResize` operation failed to update the static elm position/dimension values.
added support for named ranges and an (off-by-default) `$.whenOnScreen.nsEvents` option to always trigger namespaced events based on the range-names.
correctly handle cases when top/bottom left/right ranges overlap and cause elements to have negative net height.