add additional information to the summary seroincidence object

[kaiemjoy]

add additional information to the summary seroincidence object that includes the exact numeric noise parameters (biologic noise, measurement noise) used and the longitudinal seroresponse parameters file name and number of obervations. This will need to work for each strata as well if we use est_seroincidence_by()). the seroresponse parameters should also indicate if it was stratified (and the strata) or overall