Typemap enhancement for C#

[szekerest]

Sean,

This enhancement gives the following benefits:

1. Typemap for gdBuffer does not use global variable when marhaling the data, so
multiple imageObj can be used simultaneously.

2. imageObj.write supports to write onto a Stream object.

I have added a header for this file with my email so as to give the possibility
of receiving user's feedback on it.

Tamas

[szekerest]

csmodule.i

[sgillies@…]

Committed, r1.4

[szekerest]

Committed to Branch-4-8