FixedTimeSpanTrailingFeature sums up

[danieleTrimarchi]

There is a flaw in the design of these classes (testing, debugging)

take for example the situation :

	documentingSeedMap = DocumentationFeature(
		version=icoStudio230,
		assignee=sara,
		percentageLoad=5,
		timespan=timedelta(days=20)
	) 
	icoStudio230.addFeat(documentingSeedMap)

	documentingConnectivity = DocumentationFeature(
		version=icoStudio230,
		assignee=hippolyte,
		percentageLoad=5,
		timespan=timedelta(days=15)
	) 
	icoStudio230.addFeat(documentingConnectivity)

In this case, the two Documentation features should appear in the Gantt as separate tasks and start at the same moment.

In the Gantt chart items are grouped by name (to allow discontinuous tasks such as per holidays). So, the items are visualised as a unique item that sum up and with a unique assignee.

But in this case, the feature list for icoStudio 2.3.0 is :

Connectivity
SeedMap
PlotSignal
IcoStudio 2.3.0_testing
IcoStudio 2.3.0_documentation
IcoStudio 2.3.0_documentation
IcoStudio 2.3.0_debug
IcoStudio 2.3.0_debug 

Unique names are required. Documentation and Debug features should be tied to features, rather than soft versions.