Refs #2309

- rrset_new()
- rrset_create_data()

Refs #2309 @1.5h

Refs #2309

- Changed API a little (uint32_t was not needed, 16_t is enough to hold RDATA size)

- Compilation warnings fixed
- Helper functions for removing / adding dname removed - can be used directly

Reused wire writing from rrset (knot_rrset_to_wire).

The rdata-from-wire parsing is very similar to what compiler
does, so the code should be probably merged and reused.
Also there seems to be some problem with parsing NAPTR.

- Uncommented deep_copy_functions

Conflicts:
	src/libknot/tsig.c

The idea is to die gracefully if memory allocation fails.
Could revert this behavior later on.

Conflicts:
	src/libknot/zone/zone-tree.c

- Added functions to storing/getting dname from trie.
- Disabled until hat-trie is completed.

Conflicts:
	src/zcompile/zcompile.c

- Still needs work - dname table is missing now

- Dnames were handled wrong when freeing RDATA
- Fixed an easy memory leak

- NSEC3PARAM rdata functions added

- Reverted to slower SM in Makefile.am

Conflicts:
	src/common/errcode.h

- Needs a lot of ironing out
- Data from parser are wrong with DNSKEY and NSEC3 RRs