GUI integration

[John W. Eaton]

On 10-Aug-2012, John W. Eaton wrote:

I checked in a few more changes on the GUI branch.

The --enable-gui/--disable-gui option is now set to be enabled by
default.  If you use --disable-gui, the configure script should not
check for the gui toolkit or tools, and the Makefiles should be set up
to avoid building in the GUI directory.

With these changes, building with or without the GUI should work with
the usual autogen.sh, configure, and make process.

Two Octave binaries will be generated (octave and octave-cli).  By
default, the octave binary will start the GUI.  If building with
--disable-gui, then both binaries should be identical.

I think we are ready to merge away the GUI branch, but perhaps there
are some other issues I've missed.  Comments?

jwe