* ediff-diff.el (ediff-diff-options): clarify docstring.
(ediff-setup-diff-regions): disallow -u in ediff-diff-options.
* viper-cmd.el (viper-post-command-sentinel): protect against errors in
hooks.
(viper-add-newline-at-eob-if-necessary): add newline only if we
actually modify buffer; ignore errors if occur.