I've added STDIN support in commit bce9d61e62aa99ebc10bf75bec64d177864ee84f

I've added an explicit flag for it (the standard unix approach seems to take STDIN if you specify a solitary '-' as a commandline arg, however Trollop doesn't support this unfortunately.

As reading from STDIN is blocking, it means if I just assumed STDIN with no flags and no STDIN, then the command would just wait/hang. 

If you don't like this approach, let me know, and I'll look at how to cope with a default of STDIN instead