Non fixed mark-recapture sampling number

[bradduthie]

Currently, to simulate mark-recapture observation and analysis, values for fixed_mark and fixed_recapt need to be specified in GMSE, and the manager would have exactly these numbers of marks and recaptures in each generation, respectively. It would also be useful to, instead of specifying exact numbers, to have the manager search a general area, then mark all resources in that area. Next, the manager could search again and recapture, so the exact number is not always set and the observation process probably mimics more closely what happens in the field. This type of sampling is actually already available (observe_type = 0), so I would just need to add some code to have managers interpret some observations as marks and others as recaptures.