Added debug mode to the Sieve engine.

doc/man/sieve-test.1

src/lib-sieve-tool/sieve-tool.c

src/lib-sieve-tool/sieve-tool.h

src/lib-sieve/sieve-common.h

src/lib-sieve/sieve.c

src/lib-sieve/sieve.h

src/managesieve/managesieve-capabilities.c

src/managesieve/managesieve-client.c

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

src/sieve-tools/sieve-filter.c

src/sieve-tools/sieve-test.c

src/sieve-tools/sievec.c

src/sieve-tools/sieved.c

src/testsuite/testsuite.c