Don't speed up `fastloop()` under accelerated time

[Daxtorim]

Instead of running a fairly resource intensive loop even more often than normal, this will multiply all resource calculations by game speed. There already was a time_multiplier variable everywhere, it just wasn't really used in a way it could have been. Instead of maxing a core on my old laptop under accelerated time, now it only sits at ~60% of a core 😅.

It also has the nice side effect that the displayed resource production values are now accurate under accelerated time. As a result of that the time estimates in the build queue are showing real time as well instead of ticking down at double speed.

The midloop() and longloop() timers weren't changed, as most code is tightly build and balanced around those timings and introducing time_mulitplier variables in those functions would be a massive undertaking.