Use clock_gettime() to time steps
Simplest possible version. Still reports tick value for comparison.
Should we have the 'time_diff()' function in timers.[hc] ? I feel like that engine.c is pretty cramped and sort of a big untidy mix of stuff.
Yes, I've already started a
clocks.hto encapsulate this and handle the various possibilities. See the time-in-seconds branch. Early days so nothing to test just yet.