Further migrated implementation of extensions to new extension architecture.

...gins/comparator-i-ascii-numeric/ext-cmp-i-ascii-numeric.c

src/lib-sieve/plugins/regex/ext-regex.c

src/lib-sieve/plugins/relational/ext-relational.c

src/lib-sieve/plugins/subaddress/ext-subaddress.c

src/lib-sieve/sieve-address-parts.c

src/lib-sieve/sieve-address-parts.h

src/lib-sieve/sieve-code.c

src/lib-sieve/sieve-comparators.c

src/lib-sieve/sieve-comparators.h

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

src/lib-sieve/sieve-match-types.c

src/lib-sieve/sieve-match-types.h