Some small changes to Compute graph API to define structured datatype.
Some small changes to take into account google colab new version numbers
for the packages.
The compute graph hierarchy (Python and C++) has been modified.
It will break the code using the CG and the include and import will
have to be modified.
New function prepareForRunning is needed in CG nodes even if not used in
static mode. Without this function, code using compute graph won't build.
Christophe Favergeon
Christophe Favergeon