Add an "invisible_char" argument to set the char displayed when visibility

Add an "invisible_char" argument to set the char displayed when visibility

2000-11-09  Havoc Pennington  <hp@pobox.com>

* gtk/gtkentry.c (gtk_entry_class_init): Add an "invisible_char"
argument to set the char displayed when visibility == FALSE
(gtk_entry_create_layout): If !entry->visible, replace
all chars with the "invisible char"

* gtk/testgtk.c: Test the invisible_char deal