connect_graphes function added
prune function added: apply distance threshold to graph. Keep only distance more than threshold
graph argument added in get_cluster(self, graph=None)
testset updated
getmatindex added in SOM2.py: return a masked array with the same shape than U-matrix. Each element gives the index of the input matrix of the best matching input vector.
linewidths added for scatter in plot_graph
split graph if the main graph contains non connected subgraphes
Support added for complex numbers
fix bug with clear_output and display module
fix bug with clear_output and display module

Conflicts:

	SOM2.py
Merge branch 'complex_numbers' into dev
Revert "Merge branch 'complex_numbers' into dev"

This reverts commit 69c378716ca64c462f123f4628dd8e46bf330e9e, reversing
changes made to 35335b45f680c3b3763f9b9cd400a8c5499ba32a.
Option added to plotclusters to plot erodedmap instead of cmat
	modified:   SOMclust.py
Improvement of getLongestPath function
	modified:   SOMgraph.py
Merge branch 'dev'