Some dockapps may want to handle command line options themselves, so we
make this function optional.
Previously, if this function was skipped, then a segfault would result when
trying to access the _daContext global while first creating the dockapp
window.
Now we check if _daContext has been initialized first, and if not, we
initialize it.
In Window Maker, windows with application class "DockApp" are automatically
withdrawn. We don't want this in windowed mode. We use the application
name instead, with the usual convention of capitalizing the initial letter.