Support for APL Records

Support for APL Records

This patch adds support for APL records (rfc3123)
- Tested with the BIND and SQLite3 backends
- Tested IPv4 and IPv6
- Tested Dynamic updates
- Tested negation flag
- Closes #8379

The patch includes a documentation update (need to set release version
once accepted) and unit tests.

Contributors:
nicko@threatstop.com - Nicolas Dehaine
dshabanov@threatstop.com - Dmitry Shabanov

I (nicko@threatstop.com) agree that this code can become GPLv2 licensed.