cv::Mat to CDenseFeature conversion Factory and vice versa.

I have made a factory which directly converts any cvMat object into any(required) type of CDenseFeatures. 
and  CDenseFeature<float64_t> into the required type of cvMat (any)
thinking about this again, maybe this doesn't need to be its own class but rather just another method on the SG2CV_Factory. 

Yes lets do that lets drop the matrix from the factory name and add a method called getDenseFeatures