Improve php-doc generation.

For now own you can just add method description, parameters and those types Zephir generates for you.
Example:
```php
//  Class.zep
/**
 * Return TRUE if parameters has value with "key",
 * FALSE otherwise.
 */
public function has(string key) -> boolean
{
    return isset this->parameters[key];
}
```
```php
// stubs/Class.php
/**
 * Return TRUE if parameters has value with "key",
 * FALSE otherwise.
 *
 * @param string $key 
 * @return bool 
 */
public function has($key) {}
```