simulatedBeginTime/simulatedEndTime --- change to "Tick" terminology?

[BobbyRBruce]

Seems to me, we could clearer, and avoid using "Time" when we mean ticks, and reserve "Time" for seconds, time-stamps, etc.

It's a small nitpick but I feel like "Time" may trip up newbies.

[powerjg]

I think it's clear we need to revisit the word "time" in this and other contexts.

However, I hesitate to use gem5 terminology everywhere. For some other simulator, they might have seconds as the only unit of latency they support. Then, "tick" wouldn't make sense.