Restructured and cleaned up trace debugging and optional operand fetching.

src/lib-sieve/Makefile.am

src/lib-sieve/cmd-discard.c

src/lib-sieve/cmd-keep.c

src/lib-sieve/cmd-redirect.c

src/lib-sieve/cmd-stop.c

src/lib-sieve/ext-envelope.c

src/lib-sieve/ext-fileinto.c

src/lib-sieve/ext-reject.c

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

src/lib-sieve/plugins/body/tst-body.c

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

src/lib-sieve/plugins/date/tst-date.c

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

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

src/lib-sieve/plugins/enotify/tst-notify-method-capability.c

src/lib-sieve/plugins/enotify/tst-valid-notify-method.c

src/lib-sieve/plugins/environment/tst-environment.c

src/lib-sieve/plugins/imap4flags/cmd-flag.c

src/lib-sieve/plugins/imap4flags/ext-imap4flags-common.c

src/lib-sieve/plugins/imap4flags/tag-flags.c