Multi variable linear regression

[saroele]

I ported the regression to our new library. Main change: improved the handling of column names in the passed dataframe and now it is fully tested.

[saroele]

Maybe @JrtPec can have a quick look and merge?
Ah, we also have to write documentation, fancy the plots and provide an example notebook...

[coveralls]

Coverage increased (+20.8%) to 90.244% when pulling 16d9b86 on issue3_linreg into 3c349bc on master.

[coveralls]

Coverage increased (+20.8%) to 90.244% when pulling 16d9b86 on issue3_linreg into 3c349bc on master.

[JrtPec]

I have looked at the code, it is mostly what we've already seen before so its fine.

I have only 1 style issue: the use of **kwargs in the __init__ method. It makes the signature hard to read (you need to check the docs to see what the options are), and any IDE's prediction will not show the optional arguments.
So I propose to explicitly ask for arguments in the __init__ method.

You'll also need to deliver the material to add the analysis to the website though. We will go through that process next meeting ;-)

[saroele]

Thanks Jan. I had merged it already because of some code I'm running at 3E that needed the regression in the last pypi release.

Good point on kwargs in init. I'll change that.
I created an example notebook, but it's a bit silly without weather data (regression of one gas consumption on another :-/ ) So next monday we have to add a weather dataset for 2016, update the example and prepare website material. Nice agenda!