Calling the IPsec dialog Advanced is confusing, so rename it to IPsec.
Also in a subsequent patch there is also an Advanced group box in the IPsec dialog which would have added more confusion..

The following git file name renames occur in the vpn/l2tp folder and are in the patch file.

git mv l2tpadvancedwidget.cpp l2tpipsecwidget.cpp
git mv l2tpadvancedwidget.h l2tpipsecwidget.h
git mv l2tpadvanced.ui l2tpipsec.ui