Fix to type inferring of declared variables for code completion

When variables are declared such as:
`a : Point;` the type could be inferred by extracting 'Point' however fully qualified names such as:
`a : Autodesk.Geometry.Point` caused issues in extracting the class type. 

This submission fixes the Regex patterns used to do this string extraction for proper type extraction of declared variables in CBN for code completion.

@Benglin please review.
```type``` will never be ```null```, if we throw exception from within the constructor, then we should use ```Assert.NoThrow```.