Config override

[ghost]

Change Profile

Question	Answer
New feature	no
Bug fix	yes
BC breaks	no
Passing tests	quick an dirty tested, passed

Description

The original config override didn't work the way as was provided in the Readme. After some research I found that the issue was that the custom config were loaded after the DOMPDFModule was loaded and merged. To fix this issue, a new key dompdf_module_override was introduced that can be placed in the application or module config an will be merged after the whole config was merged.

Reason

Needed to enable remote content, but wasn't able to do it.