Add correct setting of tp_name to the full module name in Nodes.py.

Add correct setting of tp_name to the full module name in Nodes.py.

  This required a number of changes to a few files.  Basically, the
  full module name is determined in Main.py. It is then passed around
  a bit until it is used when generating tp_name.

  This change was needed because otherwise pickling of extension classes
  with full module names like sage.rings.integer.Integer would fail
  (since Python would look for integer.Integer instead).  NOTE: This is
  pickling of the extension class itself, not of instances (which could
  also fail, because the class doesn't pickle).