type T struct {
		next *T
	}

and

	type T *struct {
		next T
	}

are valid without needing forward declarations.

add "type T struct" syntax for forward struct declarations.

add "type T interface" syntax, but commented out
	(need to fix semicolons first)

R=ken
DELTA=452  (259 added, 115 deleted, 78 changed)
OCL=16580
CL=16584