reworked Pimage and model.bin
 - if bin type is "primary", then counts simply accumulate in cells
 - if bin type is "intermediate", cell values are rescaled to reflect the time duration
   (the number of iterations is carried through the life of the Pimage object)

 - there are checks that the Pimage length and nrow(chain) are equal

 - matching Pimage objects can be c(...)oncatenated together
   (there is an as.list() method for Pimage, used by c.Pimage)
 - the Pimage object carries a projection string for use by model.bin(fit, pimg = )
typo, missing method argument
renamed "ellie*" to "ElephantSeal*"
deletions