bind: replace {Read,Write}UTF16 with {Read,Write}String for string.

This is to enable more flexible encoding/decoding of Go string.
For Java, we use UTF16 to be compatible with java string.
For other languages, we will want other way to represent a string.

Change-Id: Iccd53e2eea18d37636c3c619d06cb473facef0cd
Reviewed-on: https://go-review.googlesource.com/8628
Reviewed-by: David Crawshaw <crawshaw@golang.org>

bind/java/Seq.java

@@ -36,6 +36,7 @@ public class Seq {
 	public native float readFloat32();
 	public native double readFloat64();
 	public native String readUTF16();
+	public String readString() { return readUTF16(); }
 	public native byte[] readByteArray();
 
 	public native void writeInt8(byte v);
@@ -47,6 +48,7 @@ public class Seq {
 	public native void writeFloat32(float v);
 	public native void writeFloat64(double v);
 	public native void writeUTF16(String v);
+	public void writeString(String v) { writeUTF16(v); }
 	public native void writeByteArray(byte[] v);
 
 	public void writeRef(Ref ref) {