Modified migration functions

Due to changes on ProtoGeometry.dll
- XYZ, Transform
- Line, Curve, Arc, Face
Merge branch 'CrossFade' of https://github.com/Benglin/Dynamo into CrossFade
Modified migration functions
Fixes based on line comments
Merge branch 'CrossFade' of https://github.com/Benglin/Dynamo into CrossFade
Fixed migration functions

- Removed migration functions for the nodes which are no longer
supported in ProtoGeometry.dll
- Fixed the bug which causes migration failure when the old node is not
connected to any input
Merge branch 'CrossFade' of https://github.com/Benglin/Dynamo into CrossFade
Merge branch 'CrossFade' of https://github.com/Benglin/Dynamo into CrossFade
Modified one-to-many migration functions

Helper nodes are created only when the input port of the old node is
occupied
Change into MigrationManager.SetFunctionSignature
Merge branch 'CrossFade' of https://github.com/Benglin/Dynamo into CrossFade
Merge pull request #13 from ellensi/CrossFade

Merging after visual inspection that things look alright.