Use DLL in environment variable or look in CURRENT_USER registry keys

Phill Rogersrequested to merge
techcolab.co.je/python-ghostscript:techcolab.co.je-master-patch-94366 into develop

Look for the DLL in CURRENT_USER registry keys or specify it directly in GS_DLL environment variable. Allows use of Ghostscript from PortableApps or other non-installed method for non-admin users.

Merge request reports