user32: Resend: Move character conversion logic to dde_server.d & remove todo's

[Jeff Latimer]

I have resubmitted this patch for discussion purposes.

Patch "user32/tests: Clarify the msgs to differentiate Unicode and ASCII 
in tests" cleans up existing tests for this situation and demonstrates 
the functionality.

The problem remains that the application passes to the dde/ddeml data 
that is of type LPBYTE.  This can occur as a message post or a DDEML 
call.  DDE operates in two ways. 

    * The first is the native DDE using  POST and GET messaging.  In
      this case data is passed without translation.
    * The second case uses DDEML.  When using DDEML, the data is
      translated to and from Unicode depending on the server client
      window type.
    * However, there is a third case, the hybrid.  In this case if the
      client uses messaging and posts a message, and the server uses
      DDEML translation will occur.  If the client uses DDEML and the
      server uses a get to retrieve the message translation will not occur.

The data passed to DDE/DDEML is LPBYTE but it can be Unicode or ASCII 
regardless of the interface type of the client.  In all cases the data 
is translated into the type of the server.

The issue is that the client passes data using messaging or DDEML there 
is no method in the api to inform the server whether the data is Unicode 
or not.  The only method I have determined is to use IsTextUnicode() but 
that is guessing.  However, it looks like Windows guesses too.

Can I get some advice on this as the existing code does need to be fixed.

Jeff