[svn-r29340] Purpose: Code cleanup

Description:
    - Removed many warnings:
        warning: use of old-style cast
        warning: enumeration value ‘H5D_VIRTUAL’ not handled in switch
        warning: comparison between signed and unsigned
      There are others of the same warnings and they will be taken care of
      in the next release.
    - Made some code reuse between overloads
Platforms tested:
    Linux/32 2.6 (jam)
    Linux/64 (platypus)
    Darwin (osx1010test)

c++/test/h5cpputil.cpp

@@ -195,7 +195,7 @@ void verify_val(const char* x, const char* value, const char* where, int line, c
         cerr << "*** UNEXPECTED VALUE from " << where << " should be "
              << value << ", but is " << x << " at line " << line
              << " in " << file_name << endl;
-        IncTestNumErrs();
+        //IncTestNumErrs();
         throw TestFailedException(where, "");
     }
 }