Initial parser + zone in memory commit.

src/Makefile.am

src/common/descriptor_new.c

src/common/descriptor_new.h

src/libknot/rdata.h

src/libknot/rrset.c

src/libknot/rrset.h

src/libknot/util/descriptor.c

src/libknot/util/descriptor.h

src/libknot/zone/zone-contents.c

src/libknot/zone/zone.c