* ibuffer.el (ibuffer-mode): If `show-paren-mode' is enabled,

* ibuffer.el (ibuffer-mode): If `show-paren-mode' is enabled,
disable it buffer-locally.
(ibuffer-mouse-popup-menu): Use `=' instead of `eq' to compare
`eventpt' and point.

* ibuf-ext.el (ibuffer-remove-duplicates): New function.
(ibuffer-set-filter-groups-by-mode): Use it instead of
`delete-duplicates' so we don't require cl library at runtime.
(ibuffer-insert-filter-group-before): Don't use `position' so we
don't require cl library at runtime.

* chistory.el (command-history-mode): Add interactive spec.
Improve doc string.