Populate fields rendered by complex properties

My very first pull request!

First I added an condition for properties that had `[ScaffoldColumn(true)]`. These would be rendered so can be populated.

Next I added a condition for properties that are not ValueTypes. These would have sub-properties and the the convention for MVC is to render the control Id in the format `{ParentPropertyName}`_`{ChildPropertyName}`.

It wasn't my intention to make the pull request so big (as I understand this is frowned upon). I thought I could add a pull request for each commit... but well. Clearly, I don't know my way around Git/Github, so please feel free to guide me in the right direction.

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