Improvements to the PHP lint pre-commit hook

The PHP lint pre-commit hook fails to display any output when an error
other than a parse error is detected. A simple script to reproduce this
behavior is the following:

```
<?php
use Foo\Bar;
class Bar {}
```

```
$ php -l foo.php

Fatal error: Cannot declare class Bar because the name is already in use in foo.php on line 3

Errors parsing foo.php
```

Additionally, there are quite a few comments in the hook about issues that may arise based on php.ini settings. These can be eliminated by passing the `-n` option to php (do not load php.ini), then manually specifying values for php.ini error settings using `-d`. These changes should allow the hook to work in all cases.

Note: I tried to follow the instructions at https://github.com/phpbb/phpbb3#contribute. I have a phpbb account from a long time ago, but it doesn't seem to work anymore, so I was unable to login to create a ticket. Hopefully this pull request will still be of use, despite a ticket not being created.