hdf5_der

[svn-r26640] Purpose: Fix bugs
Description:
    - Changed DataType::operator= to simply copy the id of rhs instead of
      calling H5Tcopy because, when the operator= is invoked, a different
      datatype id is created and it won't have the same characteristics as
      rhs', specifically, if the rhs represents a named datatype, "this"
      would still be a transient datatype.
    - Added a DataType constructor that takes a PredType object, and this
      constructor will cause H5Tcopy to generate another datatype id, from a
      predefined datatype.
    - Fixed various mistakes in tests.
Platforms tested:
    Linux/64 (platypus)
    Linux/32 2.6 (jam/gnu and jam/icc 15)
    SunOS 5.11 (emu development/production)