Create function skeletons for the features

[sudz123]

-Go to Features
-Check which have not been implemented
-Go to Optimizer.h
-Create a function by that respective algorithm name(An empty function with no code)
-Make sure the input and output parameters are correct
-Make a PR

[0xch4z]

I'll take this!

[sudz123]

Great, input parameters for each function is given in K.Deb book, most are similar to the ones already implemented. Output for multi-variable algorithms is an Eigen::VectorXd. Define functions with input parameters and return output x(without any code inside).