filter_time_points function, incid_ct fix-tim sim
filter_time_points function, incid_ct fix-tim sim

percolations.py
- added filter_time_points function to grab
the time steps at which a certain percent of
the cumulative epidemic size has been infected;
filter_time_points will be used to clear noise
at the beginning and end of the epidemic for
OR, which is a result of the small number of
infections at the beginning and end of an
epidemic
- episim_age_time function was changed to keep
track of incidence correctly; it now counts changes
from S to I, whereas before, it had been counting
changes from I to R
- prior time sims need to be redone

eclee25/flu-SDI-simulations-age