Alts Toolkit: Duplicate special links check is not necessarily correct

[GoogleCodeExporter]

What steps will reproduce the problem?

Attach two or more weirs to the same AltLinkID.  This is a valid modeling
case since we model weirs that have multiple overflow levels as multiple
weirs at the same location.  Unfortunately, there is a check against
multiple appends of special links that have the same AltLinkID, which
causes the special links append to fail.

What is the expected output? What do you see instead?

Apply alternative should not flag this as a problem (the error manifests as
an append special links failed message, but isn't any more detailed than
this).  Also, fix the special link check message to be more descriptive
(sure it failed, but why?...I suggest having a different message for each
case of special link check, and append it all into one error message that
will be displayed/logged).

Original issue reported on code.google.com by ArnelMan...@gmail.com on 2 Mar 2010 at 10:11

[GoogleCodeExporter]

I receive the same message even if I only try to attach one weir to an 
alternative 
link.  In this case, there is not an existing weir/orifice on the original 
model link. 
A new alt link is being added to divert some flow from the westward-flowing 
pipe toward 
the south. I have placed the model directory which includes the alternative 
folder 
"TGD_RP" onto the FTP site.  The file name is "TGD_FU_2011.zip"

Original comment by j.ruben.gonzalez.baird@gmail.com on 10 Mar 2010 at 11:36