Task #40095: Move core to namespaces
Remove compat layer for new 6.0 classes - 2
Remove the name space compatibility layer for new 6.0 classes in
t3lib/. This second patch finishes the work started with #40240
and removes the compatibily layer for the log API, and the new
configuration and rootline handling.
All class occurences that still referenced the old class names
in method headers and comments are adapted.