Set/Unset DEBUG/NDEBUG as appropriate

For a debug build:
  cmake -DCMAKE_BUILD_TYPE=Debug .

For a release build:
  cmake -DCMAKE_BUILD_TYPE=Release .

If you never set CMAKE_BUILD_TYPE, the default will remain "Release"
Encapsulate access to m_aux in TypedValueAux subclass.

Access to TypedValue.m_aux must now be via TypedValueAux.  For now,
TypedValueAux is an empty subclass with accessors to m_aux, which is
now private.  Once RefData.m_tv is moved out from under RefData._count,
we can move TypedValue.m_aux to TypedValueAux.

Removed unnecessary initialization of m_aux.u_hash from c_Vector.