Refactoring on the svm module.

Cleanup innecessary code in svm module, add docstring. Also simplify the bindings and avoid creating new objects in the wrap functions, pass arrays by reference whenever possible.

Change some names: SVC.rho_ --> SVC.intercept_

Also added tests.

git-svn-id: https://scikit-learn.svn.sourceforge.net/svnroot/scikit-learn/trunk@710 22fbfee3-77ab-4535-9bad-27d1bd3bc7d8