#29 port for the captcha vb to c#

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Hi,
i was done porting the original vb project captcha to c#, because i need it
to compile the project against mono.
the patch works against revision 749.
now i'm fixing some other typos inside the redirection handlers (lower keys
to upper keys), but at first with version 1.9.xx .net 1.1 version against
mono.
.net 1.2(2.0) will come after this steps.
:-)TSC

[TSC]

port for the captcha vb to c#