* lisp/gnus/gnus.el (gnus-info): Define with `cl-defstruct`
This makes the accessors into (inlined) functions (instead of macros), which simplifies some uses, and it makes the gnus-info-set-<foo> macros redundant since we can use `setf` instead. Remove them and update all users. (gnus-info-group, gnus-info-rank, gnus-info-read, gnus-info-marks) (gnus-info-method, gnus-info-params): Auto-defined by defstruct. (gnus-info-level, gnus-info-score): Define as a function. Add gv-setter. (gnus-info-set-group, gnus-info-set-rank, gnus-info-set-read): Remove, use `setf` instead. (gnus-info-set-marks, gnus-info-set-method, gnus-info-set-params): Define as a function. (gnus-info-set-entry): Delete function. (gnus-info--grow-entry): New function, extracted from it. (gnus-info--set-level, gnus-info--set-score): New functions, extracted from the `gnus-info-set-level` and `gnus-info-set-score` which they replace. (gnus-get-info): Define as a function. * lisp/gnus/gnus-group.el (gnus-group-edit-group-done): Use the `extend` arg of `gnus-info-set-method`. (gnus-group-sort-selected-flat): eta-reduce.