Expose 'stdin' as a sequence of ints with termination control.

Some scenarios require the ability to read stdin as a sequence of character codes. The console in .Net does not behave the same as a file. The console also has limited buffering capacity (you can't paste a large string into the console for example - try it). Call this function with arg = [-1;13] and the sequence will end if either 'enter' is pressed at the console or EOF is reached with a file.