[issue1669] allow setting username and message with transplant extension

[Greg Ward]

[oops, replied to the bug tracker rather than mercurial-devel:
reposting. sorry for dupes]

> (1) added a --username USERNAME option, to set the username used
>    for the changeset comments as transplanted into current repo
> (2) added a --message MESSAGE option, to force the message used
>    to the changeset comments that are transplanted into the current
>    repo.

Sounds handy.  As long as you're at it, what about adding -e/--edit to
allow editing the commit message?  That's consistent with qrefresh's
similar option, and I suspect that anywhere we have --message we
probably want --edit.

Greg