Add support for remote R sessions using svSocket.

Includes a new RemoteSession type for connecting to and using remote R
sessions with support for moving data back and forth between a local
fsharp R session and a remote R session. Also includes a type provider
that generates extension methods for the RemoteSession type, adding all R
functions from packages imported using the "open RProvider.{rpackage}"
syntax. The generated extension methods will not work with the current
FSharp compiler, but should be available in a future release of the
compiler.