Follow up fix for PullRequest #172

Hi Guys,

as in PR #172 discussed, the extention of the Kernel::System::Main::_Dump function is not that easy. So I propose another PullRequest to make the possible references configurable:

Added the possibility to extend possible handleable references of the Kernel::System::Main::_Dump function via a SysConfig.

Glad to hear from you.
 Thorsten