unittest: added NAPTR cornercase test
Bumped version to 1.5.2
configure: Allow lcov version 1.11
tests-extra: copy zone keys also for static zones
tests-extra: fix zone file updating
Fixed wrong AXFR-style IXFR response.

- Response had the header cleared (no ID and no QR flag).
- Also, the Question was wrongly set to AXFR. It should remain IXFR
  although the response is in AXFR format. (See RFC1995, Section 4)
ixfr: Fixed fallback to AXFR for AXFR-style IXFR.
AXFR-style IXFR master: must set the packet type
lcov: allow older versions
AXFR-style IXFR master: Fixed formatting
Merge branch 'ixfr-master-fallback' into 'master'

IXFR: falback to AXFR master-side fix

When Knot master replied to IXFR query by AXFR-style IXFR, the response was wrong in two ways:
1. Header was cleared: no ID, no QR flag
2. QTYPE was changed to AXFR

Both are wrong. The header must be set properly and the IXFR QTYPE must be preserved even if the response has the AXFR format (that's the way to distinguish it), see [RFC1995, Section 4](http://tools.ietf.org/html/rfc1995#section-4).

I removed these changes to the packet. But I'm not totally sure that there is no problem now, because the packet-processing is too obscure. @mvavrusa should review this definitely.

Tests pending.

See merge request !278
tests: new release of dnspython
Revert "ixfr: Fixed fallback to AXFR for AXFR-style IXFR."

This reverts commit e774c8a835a500cd0e66d561aa8e9f217a372f47.
IXFR: AXFR-style IXFR client side handling
tests-extra: Test for multimessage AXFR-style IXFR
Merge branch 'axfr-ixfr-client' into 'master'

Axfr ixfr client

See merge request !280
replace spin locks with mutexes, fix build on OS X

closes #293
Merge branch 'master' into dname_str_params