body of the BetweennessCentrality and the .properties
implemented the Brandes Algorithm for calculating the Betweenness Centrality
style
bugfix bc (1)
fixed plotting
debugging bc (2)
corrected properties for plotting the multi values
Merge branch 'feature/metric_betweennessCentrality' into develop

Conflicts:
	src/gtna/Exploring.java
	src/gtna/SampleExample.java