Better estimations for filter operator
Corrected minor errors in the optimizer filter operator.
Add getSolutionSet() and .getWorkset() for delta iterations

Before, the result of dataset.iterateDelta() would be the workset and
the solution set could be obtained via iteration.getSolutionSet().

This is confusing since you are not told what the result of
.iterateDelta() is supposed to be. Now, when using the result an
exception is thrown during pre-flight that advises the user to use
the two methods to get the correct dataset (work, solution).
Rename DeltaIterativeDataSet -> DeltaIteration, is no DataSet anymore

Now a user cannot mistakenly use it as a data set but is forced to use
the .getSolutionSet() and .getWorkset() methods.
added ExEnv.registerCachedFile()
StringComparators uses static StringValue.readString()
Fix generic compiler problem with Java 6
Test case for showing the still existing BulkIteration bug.
Added comments to iterative data set.
Cleaned up and  adjusted BulkIterationWithAllReducerITCase
Fix bug where a non-iterative data set is not fully consumed.
more detailed error messages for CompactingHashTable
Comparators for Value types
Straightened out ValueSerializer and ValueComparator
Remove obsolete ReflectKeyExtractorGenerator
Adjust ValueTypeInfo Generics for Java 6 compatibility.
Extension of the TypeExtractor to validate input type information and recognizing input mismatches.
More generated Tuples up to 25.
Introduced a checkstyle exception to also support TupleGeneration of more than 25 Tuples.
Support for reading from ".deflate" files
Implement clear distinction between unsplittable and serial inputs
Made Avro input formats unsplittable