DynamoDS/Dynamo — pull request #2685 by ke-yu (2014-10-13 02:00:49+00:00)
Title: Set ast node's guid properly

This pull request is to fix defect [MAGN-4659](http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-4659).

That's because when calculating change set for delta execution, we need to set modified ast node's GUID to the corresponding UI node's GUID. But the logic here is set *all modified ast nodes' GUID* to *the last UI node's GUID*:
```
foreach (var st in modifiedSubTrees)
{
...
deltaAstList.AddRange(modifiedASTList);
// WRONG - change previous AST nodes
foreach (AssociativeNode node in deltaAstList)
{
var bnode = node as BinaryExpressionNode;
...
bnode.guid = st.GUID;
...
}
}
```