- In function openDocument(), at tests of `filetype' extension,
  - Simplify tests by using QString::endsWith() in lieu of indexOf(QRegExp())
  - Add test for extension ".tar.gz";
- At function createDiagramName(), fix doc of @param name.

umbrello/umllistview.cpp
- At start of function slotDiagramCreated(), replace condition for premature
  return `m_doc->loading()' by `findItem(id)'.
  Reason: On importing Rose MDL files, diagram listview items are not created
  at all if (m_doc->loading()) is in effect.
- At function setDocument(), fix typo in doc.