* xmlschemas.c: Fixed some identity-constraint issues:
  Restructured IDC node-tables
  Allowed IDCs to resolve also to nodes of complex type with
  simple content.
  Added check for keyrefs with references to keyrefs.
  IDC target-nodes were interferring with IDC node-tables,
  since they used one list of entries only. I separated this
  one big list into 3 lists: 1 for IDC node-table entries,
  1 for _duplicates_ of IDC node-table entries and 1 for
  IDC target-nodes. More code, but cleaner and it works at last.
  Keyrefs will fail to resolve to duplicate key/unique entries.
  I thought this was already working this way, but it didn't.
  The wording of the definition for [node table] in the spec
  can lead to a scenario, where keyrefs resolve perfectly, even
  if the relevant key-sequences of the referenced key/unique have
  duplicates in the subtree. Currently only Saxon 8.5.1 is
  dissallowing resolution to duplicate entries correctly - we
  will follow Saxon here.
  Removed some intel compiler warnings (reported by
  Kjartan Maraas, bug #318517).
* pattern.c: Fixed an IDC-XPath problem when resolving to
  attributes.