commit: abolish useless "--force-editor" internal option for "hg commit"
"--force-editor" option for "hg commit" has been useless since
12721a20ed30, which makes "commands.tag()" invoke "cmdutil.commit()"
directly instead of "commands.commit()" with "--force-editor" internal
option.
This patch abolishes useless "--force-editor" internal option for "hg
commit".