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
Exactly, ` _recursive_var` doesn't really make sense. In fact, this `_recursive_var` represents the `hidden_activations` that combines all the batches till the current batch. So I guess, a meaningful name would be `_hidden_activations_subset`. I named it as `_H_sub` with a comment explaining what it is. The issue of `_hidden_activations_subset` is it's such a long name that is making the code less readable :-(