reportengine 0.12.0 available

ReportEngine 0.12.0 contains the following changes:

• bugfix: the DefaultGroupColumn.Builder was always building columns based on the zero input column

• new feature: MovingAverage sample added in the samples project

• new feature: group calculators accept labels (ie. Total, Average, Count)
• new feature: managed OutputStream/Writer ( the lifecycle of the OutputStream can be controlled by the report api or from outside)