Use Ginac expressions in CRB framework

[StephaneVeys]

Ginac expressions used in the CRB framework (for example to have beta coefficients expressions) don't depend on the geometry. We just need to perform a substitution.
It is important to evaluate quickly the beta coefficients during online step.

[prudhomm]

substitution is not an option either. We just want to not compute the geometric transformation to update the coefficient

[prudhomm]

This is old and does not follow the recent development of the CRB framework