GladeWidget: deprecated glade_widget_depends()
GladeWidgetAdaptor: deprecated glade_widget_adaptor_depends()
glade-xml-utils: glade_xml_node_is_comment() stop treating text nodes as comments
And start using type member of xmlNode struct to check node type instead of strcmp its name.

Added inline function glade_xml_node_is_comment_or_text() to use in
glade_xml_node_get_children() and glade_xml_node_next()
GladeWidget: Removed get_toplevel() cache.
This micro optimization in no longer needed and it was incomplete.
GladeProjectProperties: added license page.
Now it is posible to change license type and glade will automatically
generate it for you if you supply copyright and authors

GladeProject: save license data as comments.
Make sure comments do not contain "--"

glade-utils.c: added  _glade_util_strreplace() private function.