* yasnippet.el (yas--indent-region): Adapted and redesigned from
`yas--indent-according-to-mode'
(yas--indent-according-to-mode): Deleted.
(yas--indent): Use `yas--indent-region'.
(yas--real-line-beginning): Deleted.
(yas--update-mirrors): Always re-place active field overlay if it
exists. Pass the snippet to `yas--mirror-update-display'.
(yas--mirror-update-display): Indent the mirror text after
inserting the reflection.