Add @return type and change @param values in the comment docblocks.

There is already an issue open about this. Maybe you could merge your patch with the patch on that issue?
#2490782: Docblock improvements

+++ b/plugins/FeedsCSVParser.inc
@@ -77,7 +77,9 @@ class FeedsCSVParser extends FeedsParser {
+   * @param int $start
+   * @param int $limit

As said on the other issue, when you add @param it would be good to add a description as well. See https://www.drupal.org/node/1354#param