Timing of functions is not Windows compatible

Currently, dynesty can't be used on Windows because the timing evaluations don't work. So the time taken for a single likelihood evaluation go to zero, and then it tries to setup n_check_point and divides by zero.

@colm.talbot can I

a) Make the whole resume feature optional (I'd like to turn this off when I know that it won't take a long time, but I'm Monte Carloing 1000's of runs) b) Set that if the likelihood evaluation time is zero, the resume feature is turned off (either something is borked when calculating the time, or it is actually infinitely fast, in which case no worries about needing resume.)