F# interface to iRobot Create 2 Robotics kit

Initially targeting Mono over Dotnet Core due to better Raspberry Pi/ARM compatibility.

Project uses Dotnet Core because its project management system is so much better.

Serial IO uses https://github.com/jcurl/SerialPortStream. It is recommended to build one's own copy of libnserial.so.1 using the instructions under the "Or you can build and install in your system:" section of the main SerialPortStream readme. Also, I have found that this final step to be necessary: dotnet/core#740 (comment)