PHP 7.3 builds

A php-7.3 packages.

It can be installed with other my php build versions.
Even with system version.
Or it can pretend to be system version.

If you want to use PHP packages you'll need to add ppa:
- ppa:sergey-dryabzhinsky/backports
- ppa:sergey-dryabzhinsky/packages
to get backported packages and libraries

If you want to rebuild PHP packages you'll need to add ppa:
- ppa:sergey-dryabzhinsky/toolchain
to get backported toolchain packages

To control enabled modules - use cute tool - php-modset (php73-modset).

To use php-7.3 as system PHP - install `*php73p*` packages.
They provide alias names like system packages.
On systems with php-5 only - they not. Be careful.

If you want use additional extensions you'll need add one of PPAs:
- ppa:sergey-dryabzhinsky/php-modules
- ppa:sergey-dryabzhinsky/php7-modules

Build is Not-Thread-Safe. So it will work only with 'prefork' or 'itk' apache mpm.

== Attention! ==

@2022-03
Some backported libraries moved to backports ppa.
You should add it to the system.

@2020-03-20
Disable session garbage collector by default. Default directory cleaned by cron scripts.
You should set option `session.gc_probability` to non zero value manualy.
If your site uses custom session save path.