Replace MYSQL_inc with MYSQL_CFLAGS

Part of #1748
Replace MYSQL_lib with MYSQL_LIBS

Part of #1748
Allow overriding of LDAP_LIBS

Part of #1826
Port port
docs: recursor/running: cleanup

Mark all config vars bold, all commands/parameters preformatted,
remove double escaping.
docs: recursor/running: add new(er) commands
root MX test
test NS and CNAME pointing at the root
no fancy-records in tinydns generate-data.sh
output varies between versions
mydnsbackend: fix types pointing at root
lmdbbackend: fix types pointing at root
BAD_NETS taken from both:
http://www.iana.org/assignments/iana-ipv4-special-registry/iana-ipv4-special-registry.xhtml
and
http://www.iana.org/assignments/iana-ipv6-special-registry/iana-ipv6-special-registry.xhtml
where such a network may not be considered a valid destination
with thanks to Jack Lloyd, this works around the default Botan allocator slowing down for us during production use.
Fix typo in comment
Merge pull request #1938 from rubenk/fix-confusing-typo

Fix typo in comment
supermaster: check for missing ns records

If the master has a SOA record for a domain but
no NS records, we tried to look up the SOA record
in the supermasters table.
Merge pull request #1941 from rubenk/supermaster-handle-missing-nsrecords

supermaster: check for missing ns records
slightly improve wording of new error message for supermaster
README.md: point people directly at the new docs