Keep the gradient flowing

Second scikits.learn coding sprint

Las week took place in Paris the second scikits.learn sprint. It was two days of insane activity (115 commits, 6 branches, 33 coffees) in which we did a lot of work, both implementing new algorithms and fixing or improving old ones. This includes: * sparse version of Lasso by coordinate descent. Not (yet) merged into master, but can be looked from Olivier's branch. * new API for Pipeline. An example of this can be found in the document SVM-Anova: SVM with univariate feature selection. * documentation for the bayesian methods and cross validation: Vincent Michel contributed a lot of documentation, mainly taken from chapters of his thesis. * Ledoit-Wolf covariance estimation. * Pure python Fast ICA implementation. And the family picture, featuring (from left to right): Alexandre Gramfort, Bertrand Thirion, Virgine Fritsch, Gael Varoquaux, Vincent Michel, Olivier Grisel and me (taking the picture).