Improve php-doc generation.

For now own you can just add method description,
parameters and those types Zephir generates for you.
Change stubs extension according to #341
feature exit and die function
Merge pull request #383 from netyum/master

feature exit and die function
if phpversion < 5.6 for IS_CONSTANT_ARRAY
Added const modifiers for php 5.6+
Merge pull request #395 from ovr/php_5.6

Php 5.6
Merge pull request #389 from nkt/improve-stubs

Improve php-doc generation.