genmarshal.pl: Handle complex types, and functions with a return value but

genmarshal.pl: Handle complex types, and functions with a return value but

genmarshal.pl: Handle complex types, and functions with a return value but
	       no parameters.
genmarshal.pl gtkmarshal.* gtkwidget.c: Remove support for GDK_EVENT and
				        STYLE parameter types.