Custom fputcsv #79

Thanks for this library!

I took a look into CsvObjectFile and saw that you are utilize the PHP's own fputcsv by writing into a temp stream and catch the written line.

It would be nice, if you could write your own fputcsv that would be more customizable. Some features that could be implemented with that are:

• force enclosing fields. See https://stackoverflow.com/questions/2489553/forcing-fputcsv-to-use-enclosure-for-all-fields
• Add type formatter. The original fputcsv function formats (maybe depends on the system) numbers like 1.23. But it would be nice to define for example the decimal separator. So I can define the german comma as a decimal separator 1,23. You can imagine that this applies to any other types, e. g. date and time.

(I know, that you already have a filter mechanism. But the filter is feed with serialized line splitted by the spearator as strings, not with the raw data).