Request: Add a parameter to DataFrame.head() to control how many columns are printed
`df.head()` is my favorite way to get a quick look of a dataframe.

Until now `options.display.max_columns` was usually set to 20 which was good for me. Now that behaviour has changed and it gets set to 0. While that makes DataFrame Output look tidier it makes the use of the `head()` function can be pretty pointless if I get to see 2 or 3 columns of 20 or 30.

So I want to propose that a parameter is added to `head()` that overwrites the setting for that call.

`head()` has already a parameter for how many lines should be printed, a second parameter telling it how many columns should be printed would make a lot of sense to me and having at least one easy way to look at a DataFrame without the constraint of the default setting would be very handy.