Bug 356

The current marshaling code is not very aggressive about eliminating data
copies. Currently it only avoid copying octet sequences, and then only if the
data is stored in a message block.
But there are many other cases where the data copying can be removed, for
example, the outgoing CDR streams can always eliminate the copy, because
marshaling is immediately followed by the I/O operations, the application has no
chance to release the data.
Further, many data types (at least on regular platforms) can be marshaled
without the copies, basically all the basic types (except characters and wide
characters) and fixed sized structures if their padding matches the CDR rules (a
rare case).
On the incoming CDR streams the situation is a little different, but certainly
<in> arguments could be demarshaled without data copies, but <out> and <inout>
arguments could not.