Move handling of buttons fully in gtktreeviewcolumn. This code is less

Move handling of buttons fully in gtktreeviewcolumn. This code is less

Thu Mar  1 19:50:56 2001  Jonathan Blandford  <jrb@redhat.com>

	* gtk/gtktreeviewcolumn.c (_gtk_tree_view_column_realize_button):
	Move handling of buttons fully in gtktreeviewcolumn.  This code is
	less interrelated then it was, but it still requires the
	GtkTreeView to map it.

	* test/testtreecolumn.c: Now I can add a column to one view,
	remove it, add it to the another view, remove it, then re-add it
	to the first.  Nifty.