Allow the end of line style to be set in the record builder

When building base models on multiple boxes with different operating systems, the use of PHP_EOL in the model builder is problematic since when you rebuild you basically change every line of every file, leading to huge commits that are impossible to review.

I therefore added an eolStyle option to the Doctrine_Import_Builder class that allows you to specify which EOL markers to use.

It works perfectly fine here and the patch is attached, if the option is not specified the code remains the same as before btw so no performance loss or any possible BC break.

Thanks