Add option for to_csv() to split DataFrame in several files
Hi, I just one to ask for a new parameter in the to_csv() function of DataFrame to split the DataFrame in several files.

For example, df.to_csv(str_file,n_parts=3)

And then we get:
myfile.part1.csv
myfile.part2.csv
myfile.part3.csv

And then the csv readinf should ask which parts one wants to load.
