Allow {@inheritdoc} in PHPDoc blocks

If you begin a PHPDoc block with {@inheritdoc} (docs at http://manual.phpdoc.org/HTMLSmartyConverter/HandS/phpDocumentor/tutoria...), it is raised as an error since the sentence does not start with a capital letter or end with punctuation.

I think a sensible solution might be to ignore this problem if the doc block starts with the { character, or perhaps just ignore it if it begins with {@inheritdoc}.