lib-sieve: implemented ihave extension.

Makefile.am

configure.in

src/lib-sieve/Makefile.am

src/lib-sieve/cmd-require.c

src/lib-sieve/plugins/Makefile.am

src/lib-sieve/plugins/ihave/Makefile.am

src/lib-sieve/plugins/ihave/ext-ihave-binary.c

src/lib-sieve/plugins/ihave/ext-ihave-binary.h

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

src/lib-sieve/plugins/ihave/ext-ihave-common.h

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

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

src/lib-sieve/sieve-ast.c

src/lib-sieve/sieve-ast.h

src/lib-sieve/sieve-extensions.c

src/lib-sieve/sieve-extensions.h

src/lib-sieve/sieve-validator.c

src/lib-sieve/sieve-validator.h

tests/extensions/ihave/execute.svtest

tests/extensions/ihave/execute/ihave.sieve