avoid reserved names #5
Description
In the ISO C++ standard,
Each name that contains a double underscore _ _ or begins with an underscore followed by an uppercase letter (2.12) is reserved to the implementation for any use.
But current implementation contains such a kind of names (e.g. freeFunctions). These names are illegal, so we need to re-name them.
Since some of them are used not so frequently (e.g. __p_irr is used only in the implementation of p_irr that is used only by GreensFunction3DRadInf.cpp), it might be good to remove these free functions and define them as a member function.