Closes #20 : Group rules into few categories by priority

[PauliusMacernis]

Group rules into few categories by priority, disable rules that contradicts standards or falls into discussable "other" category (these may come back after discussed), change psr2 to psr12 (psr12 includes compatible part of psr2, psr2 is deprecated as of 2019-08-10).

[jbieliauskas]

Check out #25 on Closes.

[jbieliauskas]

Please add new lines at the end of files.

[PauliusMacernis]

Please add new lines at the end of files.

PSR2:

All PHP files MUST end with a single blank line.

As of 2019-08-10 PSR-2 has been marked as deprecated. PSR-12 is now recommended as an alternative.

PSR12:

This specification extends, expands and replaces PSR-2, ...

All PHP files MUST end with a non-blank line, terminated with a single LF.

Probably needs to be investigated more?

Update:
php-fig/fig-standards#1173

[jbieliauskas]

You're saying that it's not a php file, so doesn't have to include a LF at the end?

The line feeds are a UNIX thing. A line isn't considered a line if it isn't followed by a LF. Most standard tools require this, for example, wc -l standards/akeneo.yaml yields 13 instead of 14. It's a general practice.