[Opensg-core] Changes to OSB file format

[Carsten N. <car...@gm...>]

	Hi,

before you start screaming at me, because of the subject line, please
let me explain the issues:
1) AFAICS the current implementation writes the AttachmentMap without
binding information and hence is not able to handle multiple attachments
with the same group id on a single container.
2) Ptr mfields write size information twice, once as the binary size of
the field and then as the number of elements in the field.

These changes will make the OSB format identical to what is transmitted
in the cluster, because for writing the copyToBin methods can be used,
instead of custom code (for reading custom code can not be avoided).
This will simplify the generic parts of OSB i/o.

Loading of 1.x OSB files will still be supported, but since there was no
release of 2 I don't think we need to support the current format.

Comments ?

	Carsten