vchoi_fork

[svn-r4580] 
Purpose:
    Bug fixing
Description:
    + added operator= to PredType
    + removed 'using namespace std' from H5RefCounter.cpp because it's not
        used and leaving it there requires #include some standard header file
    + added 'using namespace std' in H5Exception.cpp

Platforms tested:
    SunOS 5.7 (arabica)
    Windows 98