Clang fixes related to Boost Serialization

The following fixes a few errors reported by Clang and seen by Boost Serialization script.
I thought something similar. But when again this would be hiding overloaded function, I think. If that should be done on a base class are lot more classes would need to be modified, but that would fix quite a number of Clang errors/warnings. There are a lot more files having exact same issue, mis-matching signature and then hiding overloaded method.