* New: In Anabatic::NetBuilder, set all the attributes as private and
create accessors and mutators.
Finish virtualising all GCell build methods and transfer them
into the NetBuilderHV class.
Build methods now return a boolean to tell if the GCell was
processed or not, to allow cascading in the "big switch".
Reorganise the "big switch" in separate sections only partially
cascading.
Truly fuse the *big switch* for channel routing and over-the-cells.
Create a new method "_do_globalSegment()" to delagate the
drawing of global segments between two GCell to the derived classes.
Jean-Paul Chaput