Simulation details GUI, mark empty stdout/stderr files

[berland]

Suggest to have a way of displaying which of these files are empty. Empty files are not so interesting to open

[jondequinor]

Yeah, OPEN is also ambiguous. I think View is closer to the truth. Also, its appearance should match the fact that it is clickable (i.e. a button). This button should be disabled if the stream is empty.