Add efficient way of concatenating multiple DataFrame objects

[totalgit74]

Whilst there is the ability to append a DataFrame to another pre-existing frame using the Append method it would be great to have a method/overload that allows for the efficient concatenation of multiple DataFrames. Whilst it is possible to loop to perform this function or chain multiple calls it does not seem like that would be a very efficient way of doing things compared to an "under the hood" implementation that could better optimise for performance.

An example of such functionality can be seen with R's rbindlist() function in the data.table library that will concatenate many large datasets efficiently. It also allows for matching by column names and filling of missing values, although that would not be needed in an initial implementation.