Prevent system commands from being called by the user directly

Use PSR-3 LoggerInterface to allow custom logging implementations.

Smarten up subEntities and return empty array for Entity items

Housekeeping git meta and tests, custom issue templates

Smaller code and docblock fixes

[skip ci]

Update funding and donation/support infos.

[skip ci]

Add Tidelift for security disclosures.
[skip ci]

Default for system commands, so they can't be executed by any user.

Completely remove Botan.io integration.

Use PSR-12 and fix code issues. Move phpcs parameters into phpcs.xml.

Save forward_date correctly to the DB.

[skip ci]