fmt.Scan: renamings, strings, errors

- implement scanning for all renamed types
	(compiler bug stops complex from being renamable,
	so it can't be tested but the code is there)
- %q %x for strings
- error handling now done with panic/recover

R=rsc
CC=golang-dev
https://golang.org/cl/1458041

src/pkg/fmt/scan.go

@@ -27,7 +27,7 @@ type readRuner interface {
 type ScanState interface {
 	// GetRune reads the next rune (Unicode code point) from the input.
 	GetRune() (rune int, err os.Error)
-	// UngetRune causes the next call to Get to return the rune.
+	// UngetRune causes the next call to GetRune to return the rune.
 	UngetRune(rune int)
 	// Token returns the next space-delimited token from the input.
 	Token() (token string, err os.Error)