Emulator reads now blocking.

Better error output CubeControl. Better debug output cubeEmu. cubeEmu
now supports sending data, but still hangs sometimes or doesn't answer
with OKs, etc.

Take a look at this to understand the protocol between hard- and
software.

Runs on Unix and creates a virtual serial port that can be opened by
CubeControl. Only responds to OK, (h)elp and (v)ersion right now.