The new LZ compression and an lztext data type based on it.

src/backend/utils/adt/Makefile

src/backend/utils/adt/lztext.c

src/backend/utils/adt/pg_lzcompress.c

src/include/catalog/pg_proc.h

src/include/catalog/pg_type.h

src/include/utils/builtins.h

src/include/utils/lztext.h

src/include/utils/pg_lzcompress.h