Support scm-layout colors: fg, bg, text and base.

Support scm-layout colors: fg, bg, text and base.

* doc/.gitignore, src/.gitignore, src/TAGS, src/gtk/ed-ffi.scm:

Added the Gtk build products/byproducts, Emacs and Edwin source file
declarations.

* src/gtk/Includes/: gdkcolor.cdecl, gdktypes.cdecl, gdkwindow.cdecl,
  gtk.cdecl, gtkrc.cdecl, gtkstyle.cdecl, gtkwidget.cdecl,
  gtkwindow.cdecl, pango-layout.cdecl:

Declare additional C functions and constants.

* src/gtk/Makefile-fragment:

Make C-generate products dependent on ALL .cdecl files, including all
of Includes/*.cdecl.

* src/gtk/compile.scm:

Factored some common code into a tricked-out sf procedure: sf+.

* src/gtk/gtk-object.scm:

Added new widget and window functions.  Do more argument type
checking.

* src/gtk/gtk.cdecl:

Removed gtk_window_new, gtk_window_set_title and
gtk_window_set_default_size to Includes/gtkwindow.cdecl.

* src/gtk/gtk.pkg:

Export new widget, window and color procedures.

* src/gtk/scm-layout.scm:

Uncomment trace statements; implement trace as a syntactic keyword.
Comment out visual and colormap GdkWindowAttr settings.  Added
accessors and mutators for the widget's four GTK_STATE_NORMAL colors.