Update DataFrame.to_latex() to have more flexibility

[sglyon]

The simple library matrix2latex has a lot of functionality packed into a single function. I think capturing some of those features in the current DataFrame.to_latex() method would make to_latex() much more useful.

The flexibility I am talking about is being able to do these types of things:

• pass in arbitrary environment names
• specify the justification of each column (as well as vertical rules between them)
• natural handling for latex symbols like \infty
• insert captions and labels into the tabular environment

[juejung]

+1