Cleanup campaign for function name in execeptions

Summary

While working on #670 (closed) I noticed many *FileReader classes throw exceptions claiming to be from FileReader::position (a copy and paste which as not updated). These should use __FUNCTION__ (gcc) or __func__ (C++11)

If we decide on C++11, then a second part of this could be to replace __FUNCTION__ throughout the code base with __func__