Simplified error handling; in particular the changes in the preceeding commits.

src/lib-sieve/cmd-discard.c

src/lib-sieve/cmd-redirect.c

src/lib-sieve/ext-reject.c

src/lib-sieve/plugins/enotify/cmd-notify.c

src/lib-sieve/plugins/enotify/ext-enotify-common.c

src/lib-sieve/plugins/enotify/mailto/ntfy-mailto.c

src/lib-sieve/plugins/enotify/sieve-ext-enotify.h

src/lib-sieve/plugins/notify/cmd-notify.c

src/lib-sieve/plugins/vacation/cmd-vacation.c

src/lib-sieve/sieve-actions.c

src/lib-sieve/sieve-actions.h

src/lib-sieve/sieve-error-private.h

src/lib-sieve/sieve-error.c

src/lib-sieve/sieve-error.h

src/lib-sieve/sieve-interpreter.c

src/lib-sieve/sieve-result.c

src/lib-sieve/sieve-result.h

src/lib-sieve/sieve-script.c

src/lib-sievestorage/sieve-storage.c

src/plugins/lda-sieve/lda-sieve-log.c