Fixes #15. (Incorrect word count for multi-line comments)

Details:
* In PHP, \PZ does not include LF, CR, VT, and FF, so instead one should
  use \P{Xps}: http://nikic.github.io/2011/12/10/PCRE-and-newlines.html
Merge pull request #16 from soheilhy/master

Fixes incorrect word count for multi-line comments/responses.