Rename CreateWindow() to CreateDialog() in generic wxPreferencesEditor code.

No real changes, just rename a method to avoid confusion with
wxPreferencesPage::CreateWindow().

Also return the concrete type of the dialog, not a base wxDialog, as it will
be useful for future changes.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74004 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Open generic wxPreferencesEditor at last shown page.

This is very convenient under systems using a modal dialog for the preferences
editor implementation (such as MSW), as it allows to do several changes in the
same page without having to select it manually every time.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74005 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Allow to specify the title used by wxPreferencesEditor window.

Customize the title is useful for "Settings"-style windows which are used for
editing the properties of the given object, that should be identified in the
window title, as opposed to the global program preferences.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74006 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Use "<Application> Preferences" as generic wxPreferencesEditor dialog title.

This is more appropriate than just "Preferences" under MSW and GTK which use
the generic wxPreferencesEditor, OS X has its own native version which
continues to correctly use "Preferences" for the title.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74007 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Make wxPreferencesEditor::Show() virtual.

This allows derived classes to override it to do something before/after
showing the dialog, which can be useful on the platforms where modal dialogs
are used for wxPreferencesEditor implementation.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74008 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Add wxPreferencesEditor::ShownModally().

While this is not necessary to use wxPreferencesEditor in normal scenario, it
can be useful if the program needs to handle modal dialogs in some special way.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74009 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Allow wxPreferencesEditor::Dismiss() to work when using modal dialogs too.

The modal dialog case is not really different, the dialog may still need to be
dismissed if the associated object doesn't exist any longer.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74010 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Initialize wxXmlResourceHandler members in its ctor.

Not sure if this results in any real problems but at the very least memory
checking tools give errors about reading uninitialized memory in
wxXmlResourceHandlerImpl::CreateResource() if we leave them uninitialized, so
do initialize all the pointers.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74011 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775