cherry pick from the libknot cleanup wip, this is going to be used
much more in the future for storing layer module owners both in
auth and resolver + for modules with ffi

Packet's wire memory initialization

Valgrind reported massive ammounts of conditional jumps depending on uninitialized memory in the security/protos test. This fixes it and as a bonus removes excess memset and reworks packet initialization a little bit.

See merge request !367

packet: bugfix: revert packet's wire initialization and fix it properly; knot_rrset_rr_from_wire read OOB.

Fixes #359

The previous knot_map_errno was vulnerable to stack buffer undeflow
if the input list was not terminated with a zero.

Fix building of documentation out of the source tree.

Don't release tar.gz, just tar.xz

I think it's quite safe to drop tar.gz these days and just distribute tar.xz.  What do you all think? @jvcelak @dsalzman @dtaborsky ?

See merge request !368

Add install-*-local targets for generated documentation

Somehow doc/Makefile.am had missing install-{pdf,html,info} targets - this adds support for installing sphinx-build generated files.

See merge request !366

Use separate sphinx-build cache dirs to allow parallel (jobserver) builds

This unbreaks make -jN info pdf html that was broken by reusing the same cache dir for all builds

See merge request !365

Fix lmdb detection code in configure.ac

Dynamic RDATA buffer allocation.

See merge request !356