Changed plotting API to use IDataset. This reduces the dependency of
tools and plotting on the abstract class. Many parts still cast to
AbstractDataset in order to get more data features. Therefore providing
your own IDataset implementation and expecting to get all things working
is not currently possible. However we will now make the plotting API
only dependent on a new analysis API. This will increase modularity and
allow an eclipse con project to be started.
Updated methods to reflect new usage of scisoft.anaylsis.api.