Chart, Filter, Property, TestSerializer models added and tested working.
BarChart Models
Filter, TestSerializer, Property models.
adds PieRegion, PieLabel, PieData, PieChart models - pieChart specific. Reuses - Property and Metadata existing models. Not tested.
Implemented the ChartAxis superclass, Dimension.java. Stackedchart.java currently in progress
adds sub-packages for the separate chart models
adds Color.java in the common classes
adds Line Chart models- needs review
Stackedbar chart model classes
fixes minor issues with Pie and Line chart
Improve the Stackedbar chart classes
Merge branch 'Feature-models-HAI' of https://github.com/AhmedShafei/HRForecast-WFM into Feature-models-HAI

Conflicts:
	WorkForceManagement/src/de/hrf/workforcemanagement/models/Bar.java
Finish Bar chart
Serialization of the xml (wip)
Fix Stackedbar chart and add toString methods in StackedbarChart and BarChart classes
clean repo state by removing Chart class
Merge branch 'Feature-models-HAI' into develop

Conflicts:
	WorkForceManagement/src/de/hrf/workforcemanagement/models/Chart.java
Merge branch 'develop' into Feature-graphs-main-layout

Conflicts:
	WorkForceManagement/src/de/hrf/workforcemanagement/models/Chart.java