change demo install dir to datadir/gtk+-2.0/demo

change demo install dir to datadir/gtk+-2.0/demo

2000-11-12  Havoc Pennington  <hp@pobox.com>

* demos/gtk-demo/Makefile.am (democodedir): change demo install
dir to datadir/gtk+-2.0/demo

* demos/gtk-demo/textview.c: Text widget demo; reveals all
sorts of text widget and Pango font bugs. Urgh.

* demos/gtk-demo/Makefile.am (demos): Add textview.c

* demos/gtk-demo/main.c (create_tree): Add instructions at top of
tree that you should double click to see the demo. Fix
types of variables to reflect changed return values from
GtkTreeStore and GtkTreeViewColumn constructors.

* gtk/gtktextbuffer.c (gtk_text_buffer_new): ref/sink the
newly-created buffer to prepare for GObject semantics

* gtk/testtext.c: don't leak the buffer with GObject semantics

* gtk/testtextbuffer.c: ditto