[Feature]: Removal of unused elements of datlist from SS_readdat_3.30

[yukio-takeuchi]

Describe the feature request.

SS_readdat_3.30 leaves some elements of datlist, that may be required for 3.24 but not for 3.30.
For example,

datlist[["fleetnames"]]
datlist[["surveytiming"]]
datlist[["units_of_catch"]]
datlist[["areas"]]

are defined and derived from datlist[["fleetinfo"]] in SS_readdat_3.30 but they are not used in SS_writedat_3.30 to write datfile
I suspect they are used for 3.24 but they evoled into single fleetinfo table

Describe alternatives you have considered

At least four elements in datlist described above may be removed from SS_readdat_3.30.

Statistical validity, if applicable

No response

Describe if this is needed for a management application

No response

Additional context

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[yukio-takeuchi]

I realized datlist[["fleetnames"]] are not used by SS_witedat_3.30.
howevr datlist[["fleetnames"]] are used by SS_readctl_3.30 if use_datlist is T to define ctllist[["fleetnames"]].
Also datlist[["fleetnames"]] are internally used by SS_readdat_3.30 to define other elements of datlist
This may be resoled by directly referencing datlist[["fleetinfo"]][["fleetname"]] in stead of datlist[["fleetnames"]] in SS_readctl_3.30
and by replacing datlist[["fleetnames"]] by datlist[["fleetinfo}]][["fleetname"]] or a new local object "fleetnames" which can be defined as

fleetnames <- datlist[["fleetinfo"]][["fleetname"]]

in SS_readdat_3.30.