Add SYSTEM option to include_directories(...)
Fix --plugin switch to pass path to plugin
Update protobuf target names
Add return statements to plugin methods
Replace uint64_t with protobuf cross-platform uint64

Use protobuf types to remove cross-platform problems.
Replace vector.data() => &vector[0]

vector.data() not supported in some versions of VC.
Add COMPILE_DEFINITION PROTOBUF_USE_DLL on Windows

This should probably move moved to a use file in the
future.
Set STDIN and STDOUT file descriptors to binary mode

On Windows we need to use _setmode(...) to set STDIN
and STDOUT to binary mode. Otherwise characters like
CR will be interpreted by the stream.
Replace uint64_t with protobuf type uint64

Generated code should should use protobuf's uint64
to avoid platform issues.
Add vtkSocketController to example

vtkSocketController is needed to call WSAStartup on Windows.