This function appends the transmission matrix created during
infection.net and infection.2g.net.
set_transmat(dat, del, at)The updated netsim_dat main list object.
Main netsim_dat object containing a networkDynamic
object and other initialization information passed from
netsim.
Discordant edgelist created within infection.net and
infection.2g.net.
Current time step.
This internal function works within the parent infection.net
functions to save the transmission matrix created at time step at to
the main netsim_dat class object dat.