add pattern method to antenna
added a doadod method to TUchannel
added a Fpatt method to generate a antenna pattern
correct a bug in buildGi in order to take into account all of subsegments
of a segment when one is metal
minor change (replace try except by hasattr)
add antenna pattern to show3 method, if S.tx and S.rx are radionodes
checn in bsignal __init__ for further broadcasting approach
show3 now display antenna pattern
Geomoff obsject default name changed
Merge pull request #195 from niamiot/master

+ generate a anetnna pattern
+ various display imporvement for antenna pattern
+ buildGi correclty manage subsegment