Refactoring error message on null topology in open()
Set run=false upon QueryExecution thread interruption
Corrected error message in emit()
Bugfix case with empty result set and thus thisTime == null
First implementation of derivation reader
Bugfix: wrong class name, was DatasetBase, corrected to
ComponentSpecificationBase.
For integrity check 2. test only the dataset ids for equality, not the
dataset objects because for one dataset the structure may be given or
the types may be different (sub/super types). I think the test on the id
should be sufficient here as the id is the key identifier for a dataset.
Minor changes in testing first example of derivation reader