How shold we implement the state?

[claudiofantacci]

The possibilities could be three

• do not implement the state at all and let the user define it all the time;
• implement the state in a "static" way, like OpenCV;
• implement the state using templates, like PCL.

[claudiofantacci]

A possible implementation is https://github.com/sfwa/ukf/blob/master/include/UKF/StateVector.h