Fix a problem of tag values which is not taken into account
(when equal to zero) when passing an XML object to an array.
Improve docs for AclShell.
Merge pull request #1276 from aymericderbois/2.3-XmlFixZeroValueProblem

Fix bug in Xml::_toArray Method
Prevent autoload when checking for the existence of HttpException

The class_exists check has been added in https://github.com/cakephp/cakephp/commit/4f29f58a5e9689adda104d77edf2c0cfe5101cd1#L1R28 to prevent a side effect with a PECL extension.

However if an autoloader such as the Composer one is loaded, it will try to require this `exceptions.php` file again:
```
    'HttpException' => $vendorDir . '/pear-pear.cakephp.org/CakePHP/Cake/Error/exceptions.php',
```
this will result in a "Fatal error:  Cannot redeclare class CakeBaseException"
Merge pull request #1277 from real34/patch-1

Prevent autoload when checking for the existence of HttpException
Split sentence into two sentences
Merge pull request #1279 from cakebaker/patch-1

Split sentence into two sentences
Make named capture groups compatible with older PCRE versions.

CentOS is terrible and generally contains very old versions of PCRE.
Update patterns to use more backwards compatible named capture groups.

Fixes #3821
Add missing h() calls to exception stack traces.
Add missing html escaping.

This should have been here the whole time. Many of these variables could
contain user input.
Add missing urlencoding to base/webroot.

This fixes URL generation when PHP_SELF or the request path contains
special characters.
Update version number to 2.3.5