bugfix: "Only variables should be passed by reference"

at this place 
```php
$this->restoreInlineProperties(array_pop($this->InlineProperties[$tag]));
```
I have an exception: "Only variables should be passed by reference" (at least PHP 5.5.15)
So, it would be better to define a variable:
$property = array_pop($this->InlineProperties[$tag]);
and then use it in $this->restoreInlineProperties()