Add native PHP solution for dig/exec

[d47081]

ygguser/simple_sites_directory#7

[ygguser]

There are comments under this article that contain links to ready-made php solutions. It might be easier to take some of this:

• https://purplepixie.github.io/phpdns/
• https://github.com/DaveRandom/LibDNS
• https://gist.github.com/bohwaz/ddc61c4f7e031c3221a89981e70b830c

[d47081]

I saw those libraries but using net-php library includes strict output validation for exec and tested on Yggdrasil/IPv6.

There is no support for all records yet, but in development - currently it's A, AAAA, SRV

Just I wish to see native PHP implementation, because exec requires system dependencies plus it's pretty unsafe.

[ygguser]

Here is native implementation: https://gist.github.com/bohwaz/ddc61c4f7e031c3221a89981e70b830c