-
Fix crashes on exit due to static documents outliving FontFactory, which they are not allowed to do. * Rework the statics.h system to allow lazy initialisation of dependencies, and more explicit dependency registration. * Promote Documents in helper/stock-items.cpp to the header, since it must now be available for PatternManager to register a dependency on it. Consequently rename to StockPaintDocuments for less ambiguity. * Move destruction of statics from Application dtor to main(). Now that Application contains documents, the old place was too early. * Convert all existing shared_ptr<SPDocument> to unique_ptr<SPDocument>. * Don't derive PatternManager::Category from Glib::Object. * Store the static documents in SymbolsDialog using statics.h to ensure destruction before FontFactory. * Similarly for the static documents in sp_marker_load_from_svg(), sp_gradient_load_from_svg(), and MarkerComboBox::init_combo(). Introduce cache_static_doc() to do this in an ad-hoc way, without having to create a singleton class.
