Revert type_loweing patch, remove it.
Instead publish the single interface we actually need: ConvertType().
Add the corresponding patch.
This brings cling's clang much closer to the original, making the update a lot easier.


git-svn-id: https://root.cern.ch/svn/root/trunk@49192 27541ba8-7e3a-0410-8455-c3a389f83636