add vizualization tool:
see trajectory of a node from a saved simulnet simulation
Merge pull request #100 from buguen/master

Add DEV-PyRT.ipynb and fixing bugs in Layout.py
add the cdf vizualization tool
Merge remote-tracking branch 'pytmp/master'
Path creation bug in project.py fixed
save class completely rewritten :
+ save speed increased
+ export speed increased
correct bug in project.py
Merge branch 'master' of github.com:niamiot/pylayers
update bugfix
save bugfix
correct bug in project.py
remove Tkinter dependency which did avoid pylayers working under Mac os X
Network is now a MultiDigraph( Multigraph before)
was required to correctly manage emmited power and sensitivity.
Would also simplify upcoming communication layer implementation
Merge branch 'master' of https://github.com/niamiot/pylayers

Conflicts:
	pylayers/antprop/signature.py
	pylayers/location/geometric/constraints/cla.py