[C++] Check existence of frame before accessing it in Model. Factorisation of code. If the frame does not exist, in release mode we return an undefined value. No check is done on runtime
[C++] Check existence of frame before accessing it in Model. Factorisation of code. If the frame does not exist, in release mode we return an undefined value. No check is done on runtime

fvalenza/pinocchio,fvalenza/pinocchio,fvalenza/pinocchio,fvalenza/pinocchio