fixes toString return value of min aggregation
Merge pull request #874 from vasia/fix_min_aggr_tostring

Fixes toString return value of MinAggregationFunction
Improved error handling when fetching optimized plan of programs.
Improve ConnectedComponentsExample with constantfields annotation
Aggregate Operator sets its semantic properties.
added murmurHash implementation
Minor cleanups for hash partitioner
Fixes an issue when generating a type erasure exception in TypeExtractor.
Set version to 0.6-SNAPSHOT
Make sure progress bar label is visible by making the minimum width to 20%.

Fixes #853.
Improve exception for nonexistent local files
Simplified exception stack traces when file is not found.
Exception added to open() and fixed \r\n
The DelimitedInputFormat.open() method did not check if it has parsers
registered. Added throwing an exception when no parser is registered
when calling open. CsvInputFormat does now accept windows line endings
with standards settings. The |\r\n" will be replaced by "\n_"( _ is a
space)... To prevent from errors the returned length is set to the
space. So that this byte is known as parsed and will not get interpreted
anymore.
Exemplary implementation of map function with Java 8 Lambdas.