Fixed ReadImageFile test case
Fixed migration issues

- "List.Create" is changed into "DSCoreNodesUI.CreateList"
- "List.Join" is changed into "DSCore.List.Join"
- "List.Transpose" is changed into built-in function "Transpose"
- "String.Concat" is now a VarArg node
Merge pull request #1216 from ellensi/ChocoButter-2Become1

Fixed migration issues