Add some helpful tooltips in result windows

[cwerling]

For instance, it is not obvious, what "Time" (timestamp?) and "Failures" (number of failures within the executed simulation rounds) means for the simulation result. Suggestion for further tooltips: "Rounds": "Number of rounds simulated to obtain approximated reliability value" "Reliability": "Probability of the top event NOT occurring before the mission time" "MTTF" : "Mean Time To Failure" (maybe this one is obvious)