1. Removed unused command "DynamoViewModel.CreateConnectionCommand"
2. Removed unused command "ConnectorViewModel.ConnectCommand"
3. Renamed ConnectorViewModel data members to conform to C# coding standard
Removed unused command "NodeViewModel.SetLayoutCommand"
Merge pull request #467 from Benglin/CommandRemoval

Removed three unwanted commands
fixed curve element from vertical line
Merge branch 'master' of github.com:ikeough/Dynamo
Added Zoom in and out GUI control at the top right corner.
- Limit Zoom within 10% to 400%
- Zoom in and out with button, will zoom in center of viewport
Fixed Zoom using mouse and pan issue

Zoom in using mouse will change the position of the Workspace but was not updated.
Therefore it will skip the position.
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