Proposal: Chainable (postfix) casting

Currently explicit casting can be made in prefix style:

`CType (obj, SomeType)`

which is uncomfortable in many situations:

```
CType(coll.First(Function (x) x.ID > 0), SomeType)
CType(CType(obj, SomeType).member, SomeOtherType)
```

This may be improved by adding virtual method, similar to ToString, but that exist only in language:

```
obj.ToType(SomeType)
coll.First(Function (x) x.ID > 0).ToType(SomeType)
obj.ToType(SomeType).member.ToType(SomeOtherType)
```

Such function may be currently created as extension method:

```

Public Function ToType(Of T1)(ByRef Src As Object) As T1
Return Src
End Function
```

but do not work for input casted to Object

```
Dim o As Object = ""
o.ToType(Of String).Length ' runtime error
```

and typing (Of ) with each call is redundant.