- includes not finished yet

- Fixed DO flag setting.
- Fixed RDATA setting in OPT init. There was some weird problem
  with the allocated dummy RDATA. Using stack instead.
- Flags were not initialized.
- Fixed flag setting in kdig.

- OPT RR is now a normal RRSet.
- Server stores only some EDNS options.
  (Will be changed later back to whole RR.)
- Rewritten EDNS getters and setters to use normal RRSet.
  (Option manipulation not done yet.)
- Added helper function for getting RRSet TTL.

- RRSet function removed altogether, it was not needed.

- find_rr_pos was used as an intersect operation.
- added flag to compare TTLs for intersection operation - I don't like
  this, other way would be to check if one of the TTLs is 0 and ignore
it then, but I doubt that would be transparent enough.

- mm_realloc is now static, since it was only used in rr.c anyway.

 - todo: Find file with __i386__ define or something similar
 - removed contst getter for rr rdata.
 - reused knot_rr_array_size function for size + META_SIZE like formulas

refs !205

- knot_rrset_copy now returns pointer

- knot_rrset_create_rr removed, only way to insert RR into rrset now is
  when you already have RDATA, so that we never create RRSet that is not
sorted.
- rr.h doxygenated, functions moved around a bit.

 - merging can now be done directly using knot_rrs_t

 - tests are passing, however some work is still pending, namely storage
   of additionals for freeing.
 - removed some obsolete node API functions

- Do not merge incoming RRs
- Duplicated add/remove checks improved in ddns
- Remove stuff directly from RRSet, do not return

- only basic functionality with leaks