GSoC 2014: Standard Extreme Learning Machines

Finished implementing the standard extreme learning machines (ELMs). I am getting the following results with 550 hidden neurons against the digits datasets,

Training accuracy using the logistic activation function: 0.999444
Training accuracy using the tanh activation function: 1.000000

Fortunately, this algorithm is much easier to implement and debug than multi-layer perceptron :).
I will push a test file soon.

@ogrisel , @larsmans
Happy that it helps.

While this would be a huge method, you can read everything in one place and retain what the function does.  In my opinion, it's easier to review and to understand the actual implementation.  In general, we tend to do all the validation in the `fit` method. Some function helpers are sometimes used whenever this could factorized among several classes/functions.