simplify_reglist treats rds files on disk as cmtk reg files

[jefferis]

e.g.

  fcwb_chiangf <-
    reglist(
      system.file(
        "extdata/CMTKreg/InitialAffine/initialiseCMTKreg_ChiangFemaleTowardsFCWB.rds",
        package = 'catnat'
      ),
      cmtkreg(system.file(
        "extdata/CMTKreg/Registration/warp/FCWB_typicalbrainfemale_01_warp_m0g80c8e1e-1x26r4.list/",
        package = 'catnat'
      )),
      system.file(
        "extdata/CMTKreg/InitialAffine/finalaffine_ChiangFemaleTowardsFCWB.rds",
        package = 'catnat'
      )
    )

> fcwb_chiangf
[[1]]
[1] "/GD/dev/R/catnat/inst/extdata/CMTKreg/InitialAffine/initialiseCMTKreg_ChiangFemaleTowardsFCWB.rds"

[[2]]
[1] "/GD/dev/R/catnat/inst/extdata/CMTKreg/Registration/warp/FCWB_typicalbrainfemale_01_warp_m0g80c8e1e-1x26r4.list"
attr(,"class")
[1] "cmtkreg"   "character"

[[3]]
[1] "/GD/dev/R/catnat/inst/extdata/CMTKreg/InitialAffine/finalaffine_ChiangFemaleTowardsFCWB.rds"

attr(,"class")
[1] "reglist"
> 
> simplify_reglist(fcwb_chiangf)
[1] "/GD/dev/R/catnat/inst/extdata/CMTKreg/InitialAffine"                                                           
[2] "/GD/dev/R/catnat/inst/extdata/CMTKreg/Registration/warp/FCWB_typicalbrainfemale_01_warp_m0g80c8e1e-1x26r4.list"
[3] "/GD/dev/R/catnat/inst/extdata/CMTKreg/InitialAffine"                                                           
attr(,"class")
[1] "cmtkreg"   "character"

[jefferis]

May be because rds files do not contain reglist objects.