[Plash] Plash 1.15: Powerbox for Gtk added

[Mark Seaborn]

Plash 1.15 is now available.  See:
http://plash.beasts.org/
http://plash.beasts.org/powerbox/

This version adds a patch to Gtk which changes GtkFileChooserDialog to
use Plash's powerbox.  It works as an LD_PRELOADed library.

The change to Gtk is not straightforward, because unfortunately the
GtkFileChooserDialog interface was not intended to be used this way.
It is not a call-return style interface.  The GtkFileChooserDialog
class inherits from the classes GtkWidget, GtkWindow, etc., so
applications can expect it to provide these interfaces.  With the
powerbox patch, GtkFileChooserDialog no longer inherits from these
classes, so most methods become no-ops.  One exception is
gtk_widget_show(), which is intercepted so that it sends the message
to the powerbox manager to open the file chooser dialog box.

I've only given this limited testing.  It works with Leafpad (a simple
text editor).  It has some problems with Gnumeric -- some more signals
need to be implemented for GtkFileChooserDialog.

Other changes: I have fixed some issues that stopped programs such as
Gnumeric and Konqueror from being able to run under Plash.  fstat() is
fixed for directory FDs.  getsockname() is changed to return the
correct filename.  link() and rename() now work in more cases.  I
fixed a problem with the dynamic linker.

I have renamed the Plash shell -- which was installed as the
executable "plash" -- to "pola-shell".  The idea behind this is to
better distinguish between Plash as a whole, the Plash environment,
and the shell.  Though Plash started off as just having a shell
interface, I am de-emphasising the shell now.  Applying POLA to GUI
programs seems to be more promising because it doesn't require
changing the user interface much.  I'm keeping the name "Plash" for
now because I haven't thought of a better name.

Mark