Removed closing PHP line endings

These are useless really to have in our files.  A simple return after ?> causes mods adding to the end of that file to fail.  Their is no difference in how the software operates after removing these.

So lets just remove these guys and make everyone happier.

I used a regex to do this ([\s+]\?>\Z), so its possible that a few may of been missed.  I corrected db_last_error.php and Settings.php when SMF is modifying them.