goprotobuf: Be more liberal in text format string parsing.

Also, a minor style tweak in CompactTextString.

R=r
CC=golang-dev
http://codereview.appspot.com/5876069
diff --git a/proto/text_parser_test.go b/proto/text_parser_test.go
index c178449..6212e9e 100644
--- a/proto/text_parser_test.go
+++ b/proto/text_parser_test.go
@@ -92,6 +92,15 @@
 		},
 	},
 
+	// Quoted string with escaped apostrophe
+	{
+		in: `count:42 name: "HOLIDAY - New Year\'s Day"`,
+		out: &MyMessage{
+			Count: Int32(42),
+			Name:  String("HOLIDAY - New Year's Day"),
+		},
+	},
+
 	// Bad quoted string
 	{
 		in:  `inner: < host: "\0" >` + "\n",