Some docblocks lack blank line before @return section

Dries requested on #855324: Fix newlines in install.inc (comment #11) that we combine all the "fix newlines" issues into one patch.

Webchick suggested on #855410: Add missing doc and newlines in updater.inc (comment #7) that a better approach would be to write a script.

So let's leave this issue open, and close the others as duplicates. The idea is to write a script that would fix all the docblocks so that they have a blank line between the @param section and the @return. Or, even simpler, so that there is a blank line before the @return in each docblock.

How about some good old find/up arrow/enter for a start? :)

Not marking CNR because i don't want to stress the test bots with this patch.

The patch looks reasonable (at least at first skim) for includes/*.inc, but we actually do want a script, and there are more files in modules/* for instance that need this change.

Does the Coder module have a test/fix for this? If so, maybe we can leverage that?

How about a regex in Zend Studio file search?

Does Zend Studio do search *and replace* with a regexp? I don't know if that's acceptable anyway. The objective would be to have something anyone can run, and not everyone has Zend.

How about a PHP or shell script, or better yet, a patch to the Coder/Coder Update module?

We are doing a doc sprint to fix this up along with some other docs problems. So closing this as a duplicate of
#1310084: [meta] API documentation cleanup sprint