Centralize creation of DocumentBuilderFactory / TransformerFactory.

[langfr]

No description provided.

[jstaerk]

sorry for not yet merging could you resolve the conflicts or shall i?

[langfr]

I will have a look.
Im using the mustangproject library and validator embedded in our ERP system running on JBoss AS / Wildfly.
Attributes settings for ACCESS_EXTERNAL_DTD and ACCESS_EXTERNAL_SCHEMA are not supported in this environment.
So I probably will change my PR and add some try / catch around each seting like another contributer proposed in PR #955.

[jSpieler-zz]

Hello,
can you please add the try / catch arround for setting: ACCESS_EXTERNAL_DTD and ACCESS_EXTERNAL_SCHEMA
In the method: ZUGFeRDInvoiceImporter.setDocument() ?

Because xercesImpl-2.12.2 does not support setting this attributes.
Thank you