Hide files from previous trash dirs in :lstrash

Thanks to filterfalse.
Change "overwrite all" key from "a" to "O"

For consistency.

Thanks to willemw12.
Use "a" for append option on conflicts
Merge branch 'a-couple-more-updates'

* Hide items of currently unused trash directories.
* Use "O" for overwrite all action.
* Use "a" for append action.