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
Why would it be desirable? Why is it prudent? These words don't add anything to the paragraph. Instead, could you explain the tradeoff a bit? Why wouldn't I always want to use `'recursive_lsqr'`? This paragraph doesn't make me understand that.