From Pjotr Svetachov, "Today I found a bug in the IutputStream class when saving array

attributes in vec3b format. It looks like my compiler takes the wrong
overload and outputs integers instead of characters. The problem is
that vec3b is of type signed char and that is not the same as char (
see http://stackoverflow.com/questions/436513/char-signed-char-char-unsigned-char
) and visual studio 2013 will promote it to integer when choosing an
overload.
It looks like that the InputStream class already takes care of this
issue (if it didn't it would have read everything ok and I would have
not even stumbled upon this bug. :) )"

include/osgDB/OutputStream

@@ -92,6 +92,7 @@ public:
     // Serialization related functions
     OutputStream& operator<<( bool b ) { _out->writeBool(b); return *this; }
     OutputStream& operator<<( char c ) { _out->writeChar(c); return *this; }
+    OutputStream& operator<<( signed char c) { _out->writeChar(c); return *this; }
     OutputStream& operator<<( unsigned char c ) { _out->writeUChar(c); return *this; }
     OutputStream& operator<<( short s ) { _out->writeShort(s); return *this; }
     OutputStream& operator<<( unsigned short s ) { _out->writeUShort(s); return *this; }