Introduce AxisValueFormatter interface and SimpleAxisValueFormatter implementation
Added separated package for formatters
Separate value formatters for every chart type(breaks old code)

More classes but that simplify usage of custom formatters
Move DummyChartAnimationListener to animation package
Create package for listeners
Create package for computators
Extracted chart listeners to separated package
Rename ArcValue into SliceValue(PieChartData)
Reformat code for PieChartData