use VISUAL instead of EDITOR in histedit_mesg_filemode_change VISUAL is preferred and relying on EDITOR may cause test failures in some environments. pointed out by op and jamsek

simplify file content comparison in a regress test; suggested by op@

fix histedit -m on a commit which only changes filemode bits The commit was being miscategorized as a no-op change and dropped. Now the commit is retained and its log message is updated as expected. ok op, jamsek

remove TODO item regarding 'got send -d' support in gotd

got.1: editing merged log messages is no longer optional, tweak related wording

got.1: Mark the commit argument to cherrypick and backout optional patch by Josiah Frentsos

abort commit with merged log messages if the log message is left unmodified ok op@

avoid creation of temporary file if no merged log messages will be used

rename a variable for clarity

clarify documentation of cherrypick/backout log message recording ok jamsek

uppercase cherrypick/backout -X progress output ok jamsek

improve heuristics for prepopulated log messages Small tweak to cover the case where users specify paths to be committed such that none of the paths modified by a backout or cherrypick operation are in the commit. In this case, the logmsg ref will remain in refs/got/worktree to be used when the user does run a commit involving the affected paths. ok stsp@

fix invalid assumption in commit_path_changed_in_worktree() Make sure we have a parent id first to avoid dereferencing a NULL pointer with the got_object_open_as_commit() call. ok op@ and stsp@

extend test_delete_branch - try to delete using git - try to delete multiple branches in one go - verify the ref-list reported by the server before and after the deletion suggested / ok stsp

gotd: implement the delete-refs capability Allow clients to run "got send -d" against gotd. Clients will send a zero-id as new id for a reference and, in the special but more common case of just deleting and not updating, no pack file will be sent. ok and tweaks by stsp@