Code Block Node Edits

Changes Made :
---

1. Code review changes from https://github.com/ikeough/Dynamo/pull/718
                +Mostly involves comments
                +Also involves refactoring of the 'VariableAlreadyDeclared' method to workspace model.

2. Small fix for one problem wrt error messages.

3. Implementation of a Max Width of the Code Block Node Text box and ports

4. A simple test case for port creation
                 + Will add more complicated ones as I progress

5. Worked on adding comments
                 + Changed the designscript .dlls to make them work. Have added a pull request for the changes in
                    DesignScript here : https://github.com/lukechurch/designscript/pull/107

6. Connection swapping was only based on names
                 + Now second priority of port index matching has been added

7. Added test cases for '5' , '6' and  defect http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-590