No F1 or Fx input

[shiguowang]

This is a clear libray, please add input keyboard "F1"/"F2"

[developer239]

@shiguowang That should be simple enough. I will take a look at it tonight. 🙌

[developer239]

@shiguowang Sorry for the delay. I merged this PR #4 . Are you on windows or Mac? I also updated docs so that people run git submodule update --init --recursive after they add submodules to load dependencies properly.